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1
Zhao, Dongning. "A low-noise CMOS interface for capacitive microaccelerometers." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31715.
Full textAbstract:
The high-performance accelerometers with micro-gravity resolution and large dynamic range at very low frequencies are not only used in GPS-augmented inertial navigation, monitoring of aircrafts and space station, but also used in monitoring wind turbines for green energy. This dissertation presents the design and development of a mixed-signal, low-noise, and fourth-order sigma-delta interface circuit for the MEMS capacitive micro-gravity accelerometer. A fully-differential switched-capacitor (SC) amplifier architecture is developed with the low-frequency noise reduction through the integration of chopper-stabilization technique with lateral BJT at input stage. The effectiveness of different noise reduction techniques is also compared and verified. The application of fourth-order SC sigma-delta modulation concept to the inertial-grade accelerometer is to achieve the benefits of the digitization of the accelerometer output without compromising the resolution of the analog front-end. This open-loop interface provides 1-bit digital output stream and has the versatility of interfacing sensors with different sensitivities while maintaining minimum power dissipation and maximum dynamic range. The micromechanical accelerometers are fabricated in thick silicon-on-insulator (SOI) substrates. The accelerometer operates in air and is designed for non-peaking response with a bandwidth of 500 Hz.
2
Kampen, Robertus Petrus van. "Bulk-micromachined capacitive servo-accelerometer." [Delft] : Delft University Press, 1995. http://books.google.com/books?id=LHJTAAAAMAAJ.
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3
Guo, Fei. "Micromachined capacitive accelerometer with crab-shape." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/1282.
Full textAbstract:
Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2005Perhaps more popular than the piezoresistive type are the capacitive type of micromachined accelerometers. The capacitive accelerometer has many fine characteristics, such as simple structure, high sensitivity, strong ability of resisting disturbance, fast dynamic response and so on. It can also work under abominable condition. So it is occupying an important status in the technology of electronical measurement and being used in many kinds of metrical systems. In this paper, the capacitive accelerometer (CA) we will introduce and design is a parallel plate CA with crab-shape. It will detect the acceleration signal by the change of distance between two electrode plates, and its design standard came from the industrial requirements ofKENTRON Company. The whole paper can be divided into four main phases-introduction, study, design and analysis. At first, we have introduced the purpose and background of this thesis, and then the study and the discussion of relative literature. The content of these articles is mainly about the basic principle, types and applications of micro-sensors and this information will be very helpful to the design and analysis ofmy own CA. The course of design is primarily structure design. The main structures of CA are parallel plate structure and cylinder structure. The parallel plate structure is chosen for our CA after we did the comparison of performance and technique of making between these two types of structures. We use the concentrative mass as the top electrode plate and four beams are connected on the two sides of the plate separately.
4
Lee, Chun Ming. "Design of two-axis capacitive accelerometer using MEMS." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FLee%5Chun.pdf.
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Boga, Biter. "Modelling And Noise Analysis Of Closed-loop Capacitive Sigma-delta Mems Accelerometer." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610772/index.pdf.
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This thesis presents a detailed SIMULINK model for a conventional capacitive Σ
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accelerometer system consisting of a MEMS accelerometer, closed-loop readout electronics, and signal processing units (e.g. decimation filters). By using this model, it is possible to estimate the performance of the full accelerometer system including individual noise components, operation range, open loop sensitivity, scale factor, etc. The developed model has been verified through test results using a capacitive MEMS accelerometer, full-custom designed readout electronics, and signal processing unit implemented on a FPGA. Conventional accelerometer system with force-feedback is used in this thesis. The sensor is a typical capacitive lateral accelerometer. The readout electronics form a 2nd order electromechanical &
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modulator together with the accelerometer, and provide a single-bit PDM output, which is decimated and filtered with a signal processing unit, software implemented on a FPGA. The whole system is modeled in MATLAB-SIMULINK since it has both mechanical and electrical parts. To verify the model, two accelerometer systems are implemented. Each accelerometer system is composed of a MEMS accelerometer, readout circuit, and decimation filters. These two different designs are implemented and simulation and test results are compared in terms of output noise, operational range, open loop sensitivity, and scale factor. The first design operates at 500 kHz sampling rate and has 0.48 V/g open-loop sensitivity, 58.7 µ
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Hz resolution, ±
12g operation range, and 0.97*10-6 g/(output units) scale factor, where these numbers are in close agreement with the estimated results found with simulations. Similarly, the second design operates at 500 kHz sampling rate and has 0.45 V/g open-loop sensitivity, 373.3 µ
g/&
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Hz resolution, ±
31g operation range, and 2.933*10-6 g/(output units) scale factor, where these numbers are also close to the estimated results found with simulations. Within this thesis study, an accelerometer sensing element design algorithm is also proposed which is based on the theoretical background obtained in accelerometer system SIMULINK model. This algorithm takes the requirements of the desired accelerometer as input and outputs the dimensions of the minimum noise accelerometer satisfying these requirements. The algorithm is extended to design three different accelerometer structures. An accelerometer sensing element is designed using the proposed design algorithm and tested in order to see performance matching of the algorithm. The designed accelerometer has ±
33.02g operational range and 155µ
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Hz noise where these numbers matches with the values found by the algorithm
6
Wang, Lin. "Mechanics of micro capacitive accelerometer with u-shape cantilever beam." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/2616.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2005.Due to an increasing in industrial micromation need in recent years, the use of micro accelerometers has been highly increased. Consecutively, this has promoted research activities in this field; capacitive accelerometers also have got high concern at large. As a research project of the Kentron in South Africa, this thesis deals with a theoretical model for a one-dimensional micro capacitive accelerometer with U-shape cantilever beam. The properties of the small angle tilted-plate capacitor have been analyzed; the capacitance equation and electrostatic force equation of this kind capacitor have been derived. The sensing element of this accelerometer consists of an inertial mass connected with two cantilever beams. The vibration modes analysis to the sensing element was accomplished by using CoventorWare2004's MemMech module, the result indicates that the main vibration mode can cause the capacitance change observably and the effect of the other modes to the capacitance can be ignored, which satisfied the purpose of the design. In the process of deriving the linearizing acceleration equation, the angle of the inertial mass caused by the deformation of the U-shape cantilever beam was taken into account as well as the electrostatic force between the two electrodes, thus the more precise acceleration linear equation was obtained. The sensitivity equation was derived through the acceleration linear equation, the relationship between the main parameters of the system and the sensitivity has been analyzed. The differential structure of this micro capacitive accelerometer was also analyzed; the linearizing acceleration equation and sensitivity equation of this kind structure were derived, it has been proven that the sensitivity of this structure is twice than the normal structure approximately. The maximum detectable signal was obtained in terms of the fracture strength of the cantilever beam and the maximum displacement of the inertial mass. The minimum detectable signal was obtained in terms of the thermal noise analysis. In the process of the dynamic analysis, the forced vibration produced by the sinusoidal periodic force and sinusoidal periodic moment was analyzed and the transient capacitance equation was derived, this proved the system has good dynamic character in theory. The system was simulated and analyzed by using CoventorWare2004's Saber module. The initial capacitance analysis indicates the relationship between the voltage and the initial capacitance, the result is close to the analytic model. The resonance frequencies analysis indicates that the main dimensions of the sensing element can determine the resonance frequencies and each vibration mode's sequence, the initial dimensions of the sensing element was proved reasonable by analyzing. Sensitivity analysis and Monte Carlo analysis indicate the effect of the sensing element's normal manufacturing tolerance to the system's frequency is small. Impact of plate curvature analysis indicates the effect of the inertial mass's deformation caused by the surface stress to the capacitance is small. Transient analysis obtained the system's transient displacement curve of six directions and transient capacitance curve in normal terms; this proved the system has good dynamic character in the simulating environment.
7
Yazicioglu, Refet Firat. "Surface Micromachined Capacitive Accelerometers Using Mems Technology." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1093475/index.pdf.
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Micromachined accelerometers have found large attention in recent years due
to their low-cost and small size. There are extensive studies with different
approaches to implement accelerometers with increased performance for a number of
military and industrial applications, such as guidance control of missiles, active
suspension control in automobiles, and various consumer electronics devices. This
thesis reports the development of various capacitive micromachined accelerometers
and various integrated CMOS readout circuits that can be hybrid-connected to
accelerometers to implement low-cost accelerometer systems.
Various micromachined accelerometer prototypes are designed and optimized
with the finite element (FEM) simulation program, COVENTORWARE, considering
a simple 3-mask surface micromachining process, where electroplated nickel is used
as the structural layer. There are 8 different accelerometer prototypes with a total of
65 different structures that are fabricated and tested. These accelerometer structures occupy areas ranging from 0.2 mm2 to 0.9 mm2 and provide sensitivities in the range
of 1-69 fF/g.
Various capacitive readout circuits for micromachined accelerometers are
designed and fabricated using the AMS 0.8 µm n-well CMOS process, including a single-ended and a fully-differential switched-capacitor readout circuits that can operate in both open-loop and close-loop. Using the same process, a buffer circuit with 2.26fF input capacitance is also implemented to be used with micromachined gyroscopes. A single-ended readout circuit is hybrid connected to a fabricated accelerometer to implement an open-loop accelerometer system, which occupies an area less than 1 cm2 and weighs less than 5 gr. The system operation is verified with various tests, which show that the system has a voltage sensitivity of 15.7 mV/g, a nonlinearity of 0.29 %, a noise floor of 487 Hz µ
g , and a bias instability of 13.9 mg, while dissipating less than 20 mW power from a 5 V supply. The system presented in this research is the first accelerometer system developed in Turkey, and this research is a part of the study to implement a national inertial measurement unit composed of low-cost micromachined accelerometers and gyroscopes.
8
Good, Daniel (Daniel Albert) 1979. "Design of a low power capacitive sensor for a micromachined accelerometer." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16840.
Full textAbstract:
Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (leaves 72-73).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Anew possible commercial application for a micromachined accelerometer is for use in handheld devices such as personal digital assistants and cellular phones, as an intuitive method of data entry which does not consume space on the ever-shrinking exterior. These devices are battery powered, which imposes stringent power consumption limitations on any hardware added. To make an accelerometer a viable addition to a handheld device, a low power version was designed, with the other device parameters, such as measurement range and noise performance, tailored to be suitable for use in a handheld. The final design measures ±3 g's of acceleration with approximately 140 [mu]g/ [square root of]Hz of noise, consuming only 200 [mu]W of power.
by Daniel Good.
M.Eng.and S.B.
9
Guney, Metin G. "High Dynamic Range CMOS-MEMS Capacitive Accelerometer Array with Drift Compensation." Research Showcase @ CMU, 2018. http://repository.cmu.edu/dissertations/1155.
Full textAbstract:
This thesis explains the design, fabrication and characterization steps of a high dynamic range CMOS-MEMS capacitive accelerometer array and on-chip environmental sensors for bias drift compensation. Inertial navigation under harsh environments requires a high dynamic range accelerometer that can survive and provide continuous readout accuracy through shock events, while having a large dynamic range to capture fine-scale motions. The dynamic range target is set as 156 dB in accordance with navigation standard macro-electromechanical accelerometers, which corresponds to around 1 mG acceleration resolution in 50 kG input range. The small accelerometer cell design ensures shock survivability (e.g. up to 50 kG) by keeping the stress at the anchors below the fracture strength of thin-film oxide. Arraying multiple accelerometer cells in parallel lowers the fundamental thermomechanical noise limit set by the small mass of the individual accelerometer cells. Resonance frequency staggering between accelerometer cells suppresses ring-down oscillations. Parasitic capacitance of the high-impedance transduction signal is important to mitigate; undercut of the underlying silicon substrate and an aluminum etch of the top metal layer, incorporated in the CMOS-MEMS process flow, reduces the parasitic capacitance and improves sensitivity. PTAT temperature sensors, piezoresistive stress sensors and resonator-oscillators integrated across the accelerometer chip provide high-resolution environmental measurements for the compensation of long-term bias and scale factor drift. Simultaneous measurements from the accelerometer and environmental sensors demonstrate the correlation between environmental variations and long-term drift. Finite-element analysis shows that the scale factor stability of the accelerometer can be improved up to 1 ppm given the sensor array’s measurement resolution. The CMOS-MEMS accelerometer system-on-chip is fabricated in a TowerJazz 0.18 μm CMOS process. The post-CMOS MEMS processing steps are tuned to reduce the top metal milling and sidewall polymer deposition. A reactive ion etch recipe is developed for the removal of the top metal in order to reduce the parasitic capacitance and eliminate the risk of metal creep at spring beam anchors, thereby improve the bias stability. The PTAT temperature sensors have 3.1 mV/K measured sensitivity and 7.1 mK resolution with high repeatability. The compensation of the accelerometer readout for temperature variations down to 7.1 mK translates to 2.6 ppm scale factor stability for the accelerometer. The characterization of the stress sensors through the application of normal stress on the device package leads to an uncertainty in the amount of stress transferred to the stress sensors on the chip surface. The maximum measured stress sensitivity is 36.5 pV/Pa, which leads to 24.7 kPa stress resolution and translates to 1.7 ppm scale factor stability for the accelerometer without taking the stress attenuation into account. The measured sensitivity sets a lower bound on the sensitivity of the stress sensors implying that the stress resolution and the corresponding accelerometer scale factor stability is higher in practice. The measured frequency stability of the resonator-oscillator is 0.4 ppm, thereby the resonance frequency based variations of the accelerometer readout can be compensated to reach up to 0.8 ppm scale factor stability. However, the initial drift in the resonance frequency of the oscillators due to dielectric charging requires a long wait-time before these sensors can be used for accelerometer drift compensation. The accelerometer array is demonstrated to have 23.7 mG/√Hz noise floor and 70 mG bias stability. The maximum input acceleration applied on the device is limited to 4 kG by the split Hopkinson bar test setup. Improvement of the setup to transfer acceleration amplitudes up to 50 kG should validate the designed input range of the accelerometer array and lead to 117 dB dynamic range for the current design. The measurement bandwidth is fundamentally set by the 126 kHz resonance frequency of the accelerometer cells and can be further limited by filtering the readout signal to attenuate the transient oscillations faster. The nonlinearity of the accelerometer response is better than 1.2% in ±10 kG input range; however, it gets up to 19.0% in ±50 kG maximum input range. The long term bias drift of the accelerometer is shown to be correlated with the temperature and stress variations. Compensation of the accelerometer readout based on the stress and temperature sensor measurements leads to an observable improvement in the long term drift. However, the bias stability of the accelerometer is limited by excessive flicker noise in the system, which is believed to result from noise folding from higher frequencies. Suppression of the flicker noise in the system should allow for a more detailed study of the effect of environmental variations on the accelerometer readout and evaluation of more elaborate fitting algorithms for model based prediction and compensation of the bias drift to reach the target bias stability and dynamic range.
10
Sonmez, Ugur. "Capacitive Cmos Readouts For High Performance Mems Accelerometers." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613068/index.pdf.
Full textAbstract:
MEMS accelerometers are quickly approaching navigation grade performance and navigation market for MEMS accelerometer systems are expected to grow in the recent years. Compared to conventional accelerometers, these micromachined sensors are smaller and more durable
but are generally worse in terms of noise and dynamic range performance. Since MEMS accelerometers are already dominant in the tactical and consumer electronics market, as they are in all modern smart phones today, there is significant demand for MEMS accelerometers that can reach navigation grade performance without significantly altering the developed process technologies.
This research aims to improve the performance of previously fabricated and well-known MEMS capacitive closed loop &Sigma&Delta
accelerometer systems to navigation grade performance levels. This goal will be achieved by reducing accelerometer noise level through significant changes in the system architecture and implementation of a new electronic interface readout ASIC. A flexible fourth order &Sigma
&Delta
modulator was chosen as the implementation of the electro-mechanical closed loop system, and the burden of noise shaping in the modulator was shifted from the mechanical sensor to the programmable electronic readout. A novel operational transconductance amplifier (OTA) was also designed for circuit implementation of the electronic interface readout. Design and fabrication of the readout was done in a standard 0.35 µ
m CMOS technology. With the newly designed and fabricated readout, single-axis accelerometers were implemented and tested for performance levels in 1g range. The implemented system achieves 5.95 µ
g/sqrt Hz, 6.4 µ
g bias drift, 131.7 dB dynamic range and up to 37.2 g full scale range with previously fabricated dissolved epitaxial wafer process (DEWP) accelerometers in METU MEMS facilities. Compared to a previous implementation with the same accelerometer element reporting 153 µ
g/sqrtHz, 50 µ
g bias drift, 106.8 dB dynamic range and 33.5 g full scale range
this research reports a 25 fold improvement in noise, 24 dB improvement in dynamic range and removal of the deadzone region.
11
Kepenek, Reha. "Capacitive Cmos Readout Circuits For High Performance Mems Accelerometers." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609310/index.pdf.
Full textAbstract:
This thesis presents the development of high resolution, wide dynamic range sigma-delta type readout circuits for capacitive MEMS accelerometers. Designed readout circuit employs fully differential closed loop structure with digital output, achieving high oversampling ratio and high resolution. The simulations of the readout circuit together with the accelerometer sensor are performed using the models constructed in Cadence and Matlab Simulink environments. The simulations verified the stability and proper operation of the accelerometer system. The sigma-delta readout circuit is implemented using XFab 0.6 µm CMOS process. Readout circuit is combined with Silicon-On-Glass (SOG) and Dissolved Wafer Process (DWP) accelerometers. Both open loop and closed loop tests of the accelerometer system are performed. Open loop test results showed high sensitivity up to 8.1 V/g and low noise level of 4.8 µ
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Hz. Closed loop circuit is implemented on a PCB together with the external filtering and decimation electronics, providing 16-bit digital output at 800 Hz sampling rate. High acceleration tests showed ±
18.5 g of linear acceleration range with high linearity, using DWP accelerometers. The noise tests in closed loop mode are performed using Allan variance technique, by acquiring the digital data. Allan variance tests provided 86 µ
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Hz of noise level and 74 µ
g of bias drift. Temperature sensitivity tests of the readout circuit in closed loop mode is also performed, which resulted in 44 mg/º
C of temperature dependency. Two different types of new adaptive sigma-delta readout circuits are designed in order to improve the resolution of the systems by higher frequency operation. The two circuits both change the acceleration range of operation of the system, according to the level of acceleration. One of the adaptive circuits uses variation of feedback time, while the other circuit uses multi-bit feedback method. The simulation results showed micro-g level noise in closed loop mode without the addition of the mechanical noise of the sensor.
12
Mokhtari, Mir. "Advanced ΣΔΜ control systems for MEMS capacitive sensing accelerometers." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419157.
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Zeimpekis, Ioannis. "Development and implementation of a deflection amplification mechanism for capacitive accelerometers." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/341919/.
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Micro-Electro-Mechanical-Systems (MEMS) and especially physical sensors are part of a flourishing market ranging from consumer electronics to space applications. They have seen a great evolution throughout the last decades, and there is still considerable research effort for further improving their performance. This is reflected by the plethora of commercial applications using them but also by the demand from industry for better specifications. This demand together with the needs of novel applications fuels the research for better physical sensors. Applications such as inertial, seismic, and precision tilt sensing demand very high sensitivity and low noise. Bulk micromachined capacitive inertial sensors seem to be the most viable solution as they offer a large inertial mass, high sensitivity, good noise performance, they are easy to interface with, and of low cost. The aim of this thesis is to improve the performance of bulk micromachined capacitive sensors by enhancing their sensitivity and noise floor. MEMS physical sensors, most commonly, rely on force coupling and a resulting deflection of a proof mass or membrane to produce an output proportional to a stimulus of the physical quantity to be measured. Therefore, the sensitivity to a physical quantity may be improved by increasing the resulting deflection of a sensor. The work presented in this thesis introduces an approach based on a mechanical motion amplifier with the potential to improve the performance of mechanical MEMS sensors that rely on deflection to produce an output signal. The mechanical amplifier is integrated with the suspension system of a sensor. It comprises a system of micromachined levers (microlevers) to enhance the deflection of a proof mass caused by an inertial force. The mechanism can be used in capacitive accelerometers and gyroscopes to improve their performance by increasing their output signal. As the noise contribution of the electronic read-out circuit of a MEMS sensor is, to first order, independent of the amplitude of its input signal, the overall signal-to-noise ratio (SNR) of the sensor is improved. There is a rather limited number of reports in the literature for mechanical amplification in MEMS devices, especially when applied to amplify the deflection of inertial sensors. In this study, after a literature review, mathematical and computational methods to analyse the behaviour of microlevers were considered. By using these methods the mechanical and geometrical characteristics of microlevers components were evaluated. In order to prove the concept, a system of microlevers was implemented as a mechanical amplifier in capacitive accelerometers. All the mechanical structures were simulated using Finite Element Analysis (FEA) and system level simulations. This led to first order optimised devices that were used to design appropriate masks for fabrication. Two main fabrication processes were used; a Silicon on Insulator (SOI) process and a Silicon on Glass (SoG) process. The SOI process carried out at the University of Southampton evolved from a one mask to a two mask dicing free process with a yield of over 95%, in its third generation. The SoG is a well-established process at the University of Peking that uses three masks. The sensors were evaluated using both optical and electrical means. The results from the first prototype sensor design (1HAN) revealed an amplification factor of 40 and a mechanically amplified sensitivity of 2.39V/g. The measured natural frequency of the first mode of the sensor was at 734Hz and the full-scale measurement range was up to 7g with a maximum nonlinearity of 2%. The measurements for all the prototype sensor designs were very close to the predicted values with the highest discrepancy being 22%. The results of this research show that mechanical amplification is a very promising concept that can offer increased sensitivity in inertial sensors without increasing the noise. Experimental results show that there is plenty of room for improvement and that viable solutions may be produced by using the presented approach. The applications of this scheme are not restricted only to inertial sensors but as the results show it can be used in a broader range of micromachined devices.
14
Tian, Ye. "SiC Readout IC for High Temperature Seismic Sensor System." Doctoral thesis, KTH, Integrerade komponenter och kretsar, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-213969.
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Over the last decade, electronics operating at high temperatures have been increasingly demanded to support in situ sensing applications such as automotive, deep-well drilling and aerospace. However, few of these applications have requirements above 460 °C, as the surface temperature of Venus, which is a specific target for the seismic sensing application in this thesis. Due to its wide bandgap, Silicon Carbide (SiC) is a promising candidate to implement integrated circuits (ICs) operating in such extreme environments. In this thesis, various analog and mixed-signal ICs in 4H-SiC bipolar technology for high-temperature sensing applications are explored, in which the device performance variation over temperatures are considered. For this purpose, device modeling, circuit design, layout design, and device/circuit characterization are involved. In this thesis, the circuits are fabricated in two batches using similar technologies. In Batch 1, the first SiC sigma-delta modulator is demonstrated to operate up to 500 °C with a 30 dB peak SNDR. Its building blocks including a fully-differential amplifier, an integrator and a comparator are characterized individually to investigate the modulator performance variation over temperatures. In the succeeding Batch 2, a SiC electromechanical sigma-delta modulator is designed with a chosen Si capacitive sensor for seismic sensing on Venus. Its building blocks including a charge amplifier, a multiplier and an oscillator are designed. Compared to Batch 1, a smaller transistor and two metal-interconnects are used to implement higher integration ICs in Batch 2. Moreover, the first VBIC-based compact model featured with continuous-temperature scalability from 27 to 500 °C is developed based on the SiC transistor in Batch 1, in order to optimize the design of circuits in Batch 2. The demonstrated performance of ICs in Batch 1 show the feasibility to further develop the SiC readout ICs for seismic sensor system operating on Venus.QC 20170911
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Vakili-Amini, Babak. "A Mixed-Signal Low-Noise Sigma-Delta Interface IC for Integrated Sub-Micro-Gravity Capacitive SOI Accelerometers." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10437.
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This dissertation presents the design and development of a mixed-signal low noise second-order integrated circuit (IC) for the open-loop and closed-loop operation of integrated capacitive micro- and nano-gravity accelerometers. The micromechanical accelerometers are fabricated in thick (less than 100 m) silicon-on-insulator (SOI) substrates. The IC provides the 1-bit digital output stream and has the versatility of interfacing sensors with different sensitivities while maintaining minimum power consumption (less than 5 mW) and maximum dynamic range (90 dB). A fully-differential sampled-data scheme is deployed with the ability of low-frequency noise reduction through the use of correlated double sampling (CDS) scheme. In this work, the measured resolution of the closed-loop CMOS-SOI accelerometer system, in the presence of high background accelerations, is in the micro-g (g: gravity) range. In this design, a second-order SC modulator is cascaded with the accelerometer and the front-end amplifier. The accelerometer operates in air and is designed for non-peaking response with a BW-3dB of 500 Hz. A 22 dB improvement in noise and hence dynamic range is achieved with a sampling clock of 40 kHz corresponding to a low oversampling ratio (OSR) of 40. The interface IC consumed a current of 1.5 mA from a supply of 3 V.
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Sun, Shihwoei, and 孫詩偉. "Capacitive Micro-accelerometer accurate measurement analysis." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/35964842248481233009.
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碩士中華技術學院
電子工程研究所碩士班
97
Before using accelerometer for measurement, mostly use the tradition and the gyroscope comparatively huge in volume examine tools as its quantity. But following promote technology and improve process, trend. That is becoming tiny components. This document focus on this point, build the module board of Micro-machined accelerometer ,store getting data into the Micro-processor , use program of the operational analysis and determine to get exact variation, to lead exact result of measurement.
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Tsao, Chi-Wei, and 曹吉緯. "Design of a Capacitive Tri-Axis Accelerometer." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/67624876454841681810.
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碩士國立暨南國際大學
電機工程學系
98
This work presents a capacitive tri-axis accelerometer and its associated readout circuit. In order to effectively and accurately readout the small sense capacitance of the tri-axis accelerometer, we use separate structure to reject signal coupling and residual stress for satisfying the low power consumption requirement. The micro-accelerometer sensor is realized with TSMC 0.35μm CMOS-MEMS process provided by CIC. The designed chip works at 3.3V power supply and 2MHz clock. The size of designed electrode for in-plane sensing is 4μm in width and 54μm in length, and that for out-of-plane sensing is 6μm in width and 100μm in length. The total number of electrodes used is 16 and 28 for in-plane and out-of-plane, respectively. The resulted spring constant is 0.38 N/m and 0.28 N/m for in-plane and out-of-plane, respectively. For a sensing range of 1G to 10G, the output voltage for in-plane sensing is 1.14V to 1.51V, while for out-of-plane sensing is 0.979V to 1.61V. A sensitivity of 0.032 V/G is achieved. The chip occupies an area of 1182×1134μm2, and consumes 1.987mW.
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Jiang, Kai-Yu, and 蔣鎧宇. "Development of a Polysilicon-based Capacitive Micro Accelerometer." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/69853415940846416705.
Full textAbstract:
碩士國立交通大學
機械工程系所
98
In this study, employing the polysilicon-based CMOS process, the related technique of design, fabrication, and measurement are built up to develop CMOS-MEMS capacitive accelerometer which integrate sensing circuit and MEMS structure to achieve batch fabrication. For the design of micro accelerometer, differential-pair sensing finger with gap-closing type is used to reduce the coupling effect; and a novel symmetric layout of suspension is proposed to eliminate the mismatch of spring constants in X and Y axes resulted from size deviation during fabrication, which would simplify the sensing circuit design. Furthermore, through the commercial finite-element-analysis (FEA) software ANSYSR, performances of micro accelerometer including stiffness, residual stress, self-test micro-actuator, and operation bandwidth are simulated and discussed for further verification. In order to achieve high sensitivity of micro accelerometer in the constrained die-area, the sizes of sensing fingers are optimized, and the performance shows that sensitivities of micro accelerometers with single axis design and two axes design can reach to 0.85 fF/G and 1.7 fF/G, respectively. For the fabrication of micro accelerometer, the residual stress of polysilicon structure that affects the deflection of sensing fingers is adjusted successfully by annealing process, and the database of the correlation between residual stress and annealing process is built up. Furthermore, an anti-stiction design rule is established successfully by finger test key to solve the severe stiction problem. For the measurement of micro accelerometer, scanning electron microscope (SEM, NCTU) and 3D profiler (ET-4000, NCTU) are used to determine the practical geometric sizes of fabricated accelerometers. The optical profiler (white-light interferometer, CIC) and MEMS motion analyzer (MMA, CIC) are used to characterize the deflection of sensing fingers and the dynamic response of accelerometers, respectively.
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Huang, Ying-Jui, and 黃英叡. "A Novel Design for CMOS Capacitive Vertical Accelerometer." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/92565546161195292153.
Full textAbstract:
博士國立清華大學
工程與系統科學系
97
This study presents a novel fabrication process of post-CMOS (complementary metal oxide semiconductor) with the chemical plasma etching. To release the CMOS microstructures, the shorter mean free path to increase lateral etching can be employed in the rough vacuum. The etching profile trends isotropy and the capability of lateral etching are controlled by pressure of the chamber. In addition, the chemical plasma etching can release silicon dioxide under the mask. This approach can fabricate symmetric geometry in the vertical direction to decrease the effect of CMOS–MEMS residual stress. Moreover, the thin single metal layer structures also can be fabricated by chemical plasma etching such as micro-spring. It has the characteristics of the lower spring constant to increase the displacement of the proof mass. Thus, the sensitivity can be further improved. A parallel-plate capacitive vertical CMOS accelerometer is demonstrated in this new concept of post-CMOS process. Based on this approach, the measured results show the residual stresses effect can be minimized in CMOS multilayer microstructures, and furthermore the curl-up effect of flat-plane is less than 2 µm across the 500 μm × 500 μm area. The sensitivity of the vertical CMOS accelerometer is about 3.2 mV/g, and total noise floor is 10 μV / √Hz.
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Chang, Chih-Wei, and 張智維. "The Design、Analysis and Fabrication of Capacitive Accelerometer." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/47357783537666255125.
Full textAbstract:
碩士國立交通大學
電機與控制工程系
91
The aim of this thesis is to design、manufacture a capacitive-type micro-accelerometer. It is different from device made by surface-micromaching and bulk-micromaching. Combining SOI-wafer and ICP-RIE technique, this accelerometer is made by two masks process. The sensing range is ±1g~±50g acceleration. Various structures are designed by changing the size of the device mass、spring and comb structure. By using Intellisuite simulation software, we obtain the displacement and resonant frequency of the accelerometer and compare with the theoretical value. The measuring methods are using vibrator and spinner to test the sensitivity and reliability of the accelerometer. Finally, we discuss and analyze the result of our measuring.
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Chen, Ching-Feng, and 陳慶蘴. "The fabrication of capacitive accelerometer by surface micromachining." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/41962271986679305966.
Full textAbstract:
碩士國立臺灣大學
電機工程學系研究所
86
Abstract In this thesis, a visible, movable capacitive accelerometer of comb structure has been primarily fabricated in Taiwan. Capacitive accelerometer was designed and fabricated. The polysilicon film was deposited, doped, and patterned by reactive ion etch (RIE). The integrated circuit (IC) manufacturing has become the most potential industry in the world at the coming end of the 20th century. Over the past three decades, the improved process control in silicon IC has enabled the use of materials available in IC process to fabricate complete micro-electro-mechanical systems (MEMS). There are surface-micromachining and bulk-micromachining in MEMS. Single-crystal silicon is known to be an excellent mechanical material. But double-sided processing and special handling requirements make bulk micromachining incompatible with standard IC fabrication techniques. In this research, the capacitive accelerometer was different from the ADXL 50 accelerometer by the "H" tethers of shorter foot distance preventing the main mass of accelerometer from sticking to the substrate easily. The polysilicon film was released from the surface using a sacrificial layer of phosphosilicate glass (PSG) that provided the support of the polysilicon bridge throughout the fabrication sequence. Due to the smoothnesss of the surface on silicon, large capillary forces between fabricated structures and the substrate were produced. The structure- release machine was setup to release the forces by using supercritical carbon dioxide. Since the liquid-vapor interface is not formed, capillary forces were unable to bring adjacent surfaces into contact with one another and stiction was not observed. Finally the process is complete. Through empirical study of the design, fabrication of the capacitive sensor, we will gain some starting experiences on surface micromachining in NTU.
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Wang, Chun-Chieh, and 王竣傑. "Capacitive accelerometer with capacitance to digital interface circuit design." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/26235190598520438813.
Full textAbstract:
碩士國立交通大學
電子研究所
101
A monolithic accelerometer with integrated capacitance to digital readout circuit in 0.18um CMOS MEMS process is proposed to demonstrate sensor to bit integration. The sensing range of the accelerometer is designed from -5g to 5g and the variation of the capacitance is from 441.2fF to 470fF. The sensitivity of the accelerometer is 2.88fF/g. The capacitance value of the sensing range is readout by the capacitance to pulse-width circuit to readout. The capacitance to pulse-width circuit of the sensitivity is 6.94us/pF which is equivalent to 20ns/1bit. Therefore, without any analog to digital module, the output signal can be directly interface to digital signal process. In order to get the accurate value of monolithic front-end circuits, the computer aided design flow for MEMS and IC integration is used to co-simulate the monolithic circuits with the accelerometer and to provide comprehensive analysis of the difference between the simulation and the measurement results.
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"Calibration of MEMS capacitive accelerometers using Electrical Stimulus BIST." Master's thesis, 2014. http://hdl.handle.net/2286/R.I.21039.
Full textAbstract:
abstract: The applications which use MEMS accelerometer have been on rise and many new fields which are using the MEMS devices have been on rise. The industry is trying to reduce the cost of production of these MEMS devices. These devices are manufactured using micromachining and the interface circuitry is manufactured using CMOS and the final product is integrated on to a single chip. Amount spent on testing of the MEMS devices make up a considerable share of the total final cost of the device. In order to save the cost and time spent on testing, researchers have been trying to develop different methodologies. At present, MEMS devices are tested using mechanical stimuli to measure the device parameters and for calibration the device. This testing is necessary since the MEMS process is not a very well controlled process unlike CMOS. This is done using an ATE and the cost of using ATE (automatic testing equipment) contribute to 30-40% of the devices final cost. This thesis proposes an architecture which can use an Electrical Signal to stimulate the MEMS device and use the data from the MEMS response in approximating the calibration coefficients efficiently. As a proof of concept, we have designed a BIST (Built-in self-test) circuit for MEMS accelerometer. The BIST has an electrical stimulus generator, Capacitance-to-voltage converter, ∑ ∆ ADC. This thesis explains in detail the design of the Electrical stimulus generator. We have also designed a technique to correlate the parameters obtained from electrical stimuli to those obtained by mechanical stimuli. This method is cost effective since the additional circuitry needed to implement BIST is less since the technique utilizes most of the existing standard readout circuitry already present.Dissertation/Thesis
M.S. Electrical Engineering 2014
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Tse, Colin. "Design of a Power Scalable Capacitive MEMS Accelerometer Front End." Thesis, 2013. http://hdl.handle.net/1807/35144.
Full textAbstract:
This thesis presents the design, implementation and fabrication for a 0.13μm interface to a capacitive MEMS accelerometer.
By varying the number of amplifier slices used in concurrence based on different full scale input ranges, the analog circuitry power scales as the input range scales. Due to the oversampling nature of typical accelerometer front ends, for a full-scale input increase of N times, the analog circuitry power reduces by N2 times. The front end has two signal amplification stages, with the first stage power scaled. The chip is 1.15mmx1.15mm and implemented in a 0.13μm CMOS process. The design was packaged with the MEMS accelerometer chip inside a 44 pin CQFP. Measured results show an output rms noise of 63μVrms in a 100Hz bandwidth. The total analog circuitry power scales very linearly with different full scale ranges.
A novel simple offset removal network is also shown and confirmed via measurement results.
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Shih-MengTseng and 曾式盟. "Single-Axis CMOS-MEMS Capacitive Accelerometer with Post-Processing Circuits." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/vk6xu7.
Full textAbstract:
碩士國立成功大學
電機工程學系
105
Four different structures of single-axis capacitive accelerometers are designed and implemented in this thesis. The four front-end sensors and their back-end signal processing circuits are integrated into a single chip, and two of them (the 1st and 4th accelerometer) are functional work. According to the measurement results, the 1st accelerometer has the best sensitivity, which is 35.57 mV/g with a full range of ±13 g, and its power consumption is around 0.561 mW. The 4th one has a maximum sensitivity of 45.4 mV/g with a sensing range of ± 3, and its power consumption is around 0.5676 mW. In addition, the main contribution of the post-processing circuits is to propose a differential-to-single-end differential difference amplifier (DDA) with dc bias voltage suppression, which amplifies the input differential signal only without amplifying its dc bias voltage, and it prevents the output from saturation. The proposed chip was fabricated in Taiwan Semiconductor Manufacturing Company (TSMC) 0.35 μm CMOS/MEMS 2P4M 3.3 V/5 V process and MEMS post process. The die area of this chip is 2.1282 mm × 2.4972 mm
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Wu, Kuan-Hsun, and 吳冠勳. "Design of Monolithic Integrated MEMS Capacitive Accelerometer with Readout Circuit." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/hgw5fs.
Full text
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Lee, Chen-Pin, and 李振賓. "Modeling and Control of a Capacitive Multi-Axis Micro-Accelerometer." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/65992721653444960481.
Full textAbstract:
碩士南台科技大學
機械工程系
91
This study investigates the possibility to improve the performance of a capacitive multi-axis micro-accelerometer. Despite of its advantage on the size-effect, the capacitive micro-accelerometer encounter still some drawbacks, such as weak output signal, insufficient bandwidth, poor sensitivity and nonlinear behavior. By introducing the feedback mechanism with modulation-demodulation, followed by signal processing, the desired improvement is achieved, namely clearer signal better sensitivity and more linearity. The equation is based on linear system and simulated with damping rate is 0.707. According the result of simulations, the system reaches its stability within 0.6 ms with the sensitivity of 18 mv/g for x-axis direction and the sensitivity of 23 mv/g for y-axis direction under the conditions of a 10 g external acceleration. Through a series of simulations under the conditions of a 10 g external acceleration, it is found that the system reaches its stability within 0.6 ms with the sensitivity of 18 mv/g for x-axis direction and 23 mv/g for y-axis direction. Then, the simulations with the external acceleration ranging from 5 to 50 g are conducted and its sensitivity was 18, 23mv/g. Because the acceleration of signal direction to effect x, y-axis and make them to generate the displacement. According above factor, the output signal of 2-axis is simulated with acceleration of 1-axis. First, the simulation under the conditions of a 10 g external acceleration for x-axis direction, the system reaches its stability within 6 ms with the sensitivity of 18 mv/g. It is found that the output signal of y-axis is smaller than x-axis. Second, the simulations with the external acceleration ranging from 5 to 50 g for x-axis direction are conducted and its sensitivity was 18 mv/g. Third, the simulation under the conditions of a 10 g external acceleration for y-axis direction, the system reaches its stability within 0.6 ms with the sensitivity of 23 mv/g. It is found that the output signal of x-axis direction is smaller than y-axis direction. Final, the simulations with the external acceleration ranging from 5 to 50 g for y-axis direction are conducted and its sensitivity was 23 mv/g. It is shown the proposed controllable law is expected to reach optimal sensitivity and linearity for x-axis direction and y-axis direction. In the future, the CMOS-based control electric circuits with the micro-structure of the micro-accelerometer manufactured also by CMOS technology.
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Ko, Huang-Shao, and 柯皇卲. "Fabrication and Simulation of a Multi-Axis Capacitive Micro Accelerometer." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/65387594135187292506.
Full textAbstract:
碩士南台科技大學
機械工程系
91
This work focuses on the processes of fabrication and simulation for a multi-axis capacitive micro accelerometer. By intensive cross checks among two MEMS-related application software and one Finite Element Analysis software, improvements can be made both in shortening the process of building model of the micro accelerometer and in speeding up its design verification among different software. Meanwhile the optimization for the structure design can be also realized. As for the fabrication of the micro accelerometer, a CMOS compatible UV-LIGA process, together with the technique of sacrificial layer, is proposed. Instead of conventional metallic material, the sacrificial layer in this study is made of photoresists (S1818) so that the cost of metal decomposition can be saved and the potential damage to the structural layer caused by metal etchant can also be prevented. The structural layer itself is defined by the micro mold, which consists of photoresist SU-8.It is crucial to control the temperature and time when it comes to the soft baking process for thick photoresists. To removal SU-8 photoresist, oxygen plasma etching, that was examined to be relatively effective, is employed. The etching rate is set about 4000 Å /min under 40 sccm O2 plasma at 300 mTorr and 250 Watt RF power. The principal structural layer of the micro accelerometer is fabricated by electrolyte whose composition is Ni(SO3NH2)2:NiCl2:H3BO3:NiCO3 = 350:5:30:3. The pH value of the electrolyte solution was adjusted to a value at 4. The bath of electroplating was heated and retained at temperature of 50~55°C and the plating current is fixed at 10 mA/cm2. The resulted electroplating of Ni with speed of 0.16μm/min successfully constitutes a structure layer with high aspect ratio.
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Yang, Kuilian. "Low-Noise High-Precision Readout Circuits for Capacitive MEMS Accelerometer." Thesis, 2021. http://hdl.handle.net/10754/669009.
Full textAbstract:
Over the past two decades, Micro-Electro-Mechanical System (MEMS) based accelerometers, benefiting from relatively simple structure, low-power consumption, high sensitivity, and easy integration, have been widely used in many industrial and consumer electronics applications. For the high precision accelerometers, a significant technical challenge is to design a low-noise readout circuit to guarantee the required high resolution of the entire integrated system.
There are three main approaches for improvement of the noise and offset of the readout circuit, namely auto-zero (AZ) and correlated double sampling (CDS) for the switched- capacitor (SC) circuit and chopper stabilization (CHS) for the continuous-time circuit.
This thesis investigates the merits and drawbacks of all three techniques for reading the capacitance of a low noise MEMS accelerometer developed in our group. After that, we compare the different effects of the three technologies on noise, offset, output range, linearity, dynamic range, and gain. Next, we present the design of the most suitable structure for our sensor to achieve low noise, low offset, and high precision within the working frequency. In this thesis, the design and post-layout simulation of the circuit is proposed, and the fabrication is currently in progress. The readout circuit has reached the noise floor of the sub-μg, which meets the strict requirements of low noise MEMS
capacitance-to-voltage converter. A high-performance accelerometer system is regarded
as the core of a low-noise, high-resolution geophone. We show that together with the MEMS accelerometer sensor, the readout circuit provides competitive overall system noise and guarantees the required resolution.
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CHERNG, HO YIH, and 何義成. "Design and Measurement of the Electronic Circuit for Capacitive accelerometer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/03235778710960335762.
Full textAbstract:
碩士長庚大學
電子工程研究所
93
This paper discusses the design and measurement of the overall circuit, which applys square wave to the capacitive bridge of an accelerometer. To improve the system response time and reduce the effect of the system noise, the frequency of the square wave was raised to 200KHz. Pspice was used to simulate the stable and dynamic conditions of the overall system of the electromagnetic force feedback capacitive accelerometer. The stable and dynamic characteristics measured of the implemented system are alike the simulated results.
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Chih-WeiHuang and 黃志偉. "Design and Fabrication of a Capacitive Micro Accelerometer by CMOS-MEMS." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/29550318941063087026.
Full textAbstract:
碩士國立成功大學
微電子工程研究所碩博士班
98
This thesis is contained multi-axis MEMS capacitive accelerometer. It constructs the 3D model easily and uses the finite element method (FEM) to simulate the mechanical equation by CoventorWare which is MEMS simulation software. It also provides the optimum design of the micro-accelerometer by CoventorWare. In this design, I use CMOS-MEMS 0.35 μm process by TSMC and APM to make the structure suspending through the technology of scarification layer. It will fabricate the high aspect ratio micro accelerometer. This research mentions three axis sensing accelerometer respectively and uses the CMOS process to design the instrument amplifier for readout circuit. The in-plane accelerometer is designed by capacitance sensing with instrument amplifier. The out-plane accelerometer is designed by piezo-resistive sensing with Wheatstone bridge. The sensitivity of single-axis accelerometer is 2 mV/g and is risen to 8 mV/g through multiplier to demodulate output signal. The resonant frequency of single-axis accelerometer is 3 kHz. Static capacitance of comb finger is about 120 fF. The sensitivity of dual-axis accelerometer is 0.02 fF/g and resonant frequency is located at 5 kHz. Static capacitance of comb finger is about 80 fF. The sensitivity of Z-axis accelerometer is 0.5 Ω/g and resonant frequency is located at 22 kHz. Static resistance of cantilever is about 195.04 kΩ.
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Chen, Wei-Chieh, and 陳維傑. "Design and Implementation of Reduced Structure Deflection CMOS-MEMS Capacitive Accelerometer." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/79316181399713675338.
Full textAbstract:
碩士國立清華大學
動力機械工程學系
99
This study utilize TSMC 0.35um Mixed Signal 2P4M Polycide process and post process to design and fabricate a reduced structure deflection capacitive type fully differential CMOS-MEMS accelerometer. In general, accelerometer fabricated with CMOS-MEMS process face issue of severe deflection due to residual stress. The merit of this study is to etch away polysilicon which is embedded in the bottom part of structure at the end of process, which is the same as traditional dry etching process. Field oxide(FOX), which contribute highest level of residual stress, is then be removed simultaneously. Deflection of structure can be reduced thereof. Overall characterization of the device is: (1) integrate MEMS and IC monolithically with CMOS-MEMS technique, (2) amplify sensing signal and eliminate common mode noise through fully differential sensing, and (3) etch away polysilicon under the structure to reduce deflection.
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Chiang, Cheng-Yu, and 江鎮宇. "Testing and improvement of a single-chip dual-axial capacitive micro accelerometer." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/97540516814488955802.
Full textAbstract:
碩士國立交通大學
機械工程學系
99
Based on the previous design of our group, with symmetric coil-type suspension in the micro accelerometer, here the fabrication process is further improved, sensing circuit and MEMS structure are integrated, and the electrical output signal are measured for the development of a single-chip capacitive micro accelerometer. For the structural design of micro accelerometer, differential sensing pair we used to achieve the capacitive measurement. In order to reduce side stiction, the sensing fingers are fixed at both ends in current design. At the same time, fabrication process is modified to reduce residual stress of polysilicon structure and the flaws during the whole process. For the result of the fabrication process, scanning electron microscope (SEM, NCTU) and 3D profiler (ET-4000, NCTU) are used to measured geometric sizes of fabricated accelerometers. The optical profiler (white-light interferometer, CIC) and MEMS motion analyzer (MMA, CIC) are used to characterize the deflection of proof mass and the dynamic response of accelerometer, respectively. For the electrical signal output, sensitivity of dual-axial accelerometers is shown to reach above 300 mv/G with the dynamic range of ±5G, however cross sensitivity is about 15%. The all signal self-test actuator is shown to successfully provide electrostatic force to move the proof mass. Currently, capping process of the micro accelerometer has been developed, and further package process in under way.
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Lee, Chieh-Han, and 李杰翰. "Design and Fabrication of Capacitive Accelerometer and Microphone using CMOS-MEMS Process." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/qt38cb.
Full textAbstract:
碩士國立臺北科技大學
機電整合研究所
96
CMOS-MEMS is composed of CMOS process from IC fabrication and MEMS. The elements based on CMOS-MEMS have the mechanical properties. Therefore, using CMOS-MEMS process for MEMS elements not only has the advantages of MEMS but also has the compatibility with IC fabrication. Moreover, the elements which are fabricated by CMOS-MEMS are easy to integrate with IC circuits. The study was using the standard CMOS process and MEMS post-process to develop the capacitance accelerometer and microphone. Besides, we demonstrated new processes for fabrication and new structures which could be fabricated by CMOS and be integrated with circuits on one chip. Meanwhile, we used the simulation software, ConvetorWare, to optimize the structures of three-axis accelerator and microphone. In the final steps, using RLS post-process which was provided by CIC and dry、wet etching achieved the establishment of the accelerator and microphone.
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"An Electrical-Stimulus-Only BIST IC For Capacitive MEMS Accelerometer Sensitivity Characterization." Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.46194.
Full textAbstract:
abstract: Testing and calibration constitute a significant part of the overall manufacturing cost of microelectromechanical system (MEMS) devices. Developing a low-cost testing and calibration scheme applicable at the user side that ensures the continuous reliability and accuracy is a crucial need. The main purpose of testing is to eliminate defective devices and to verify the qualifications of a product is met. The calibration process for capacitive MEMS devices, for the most part, entails the determination of the mechanical sensitivity. In this work, a physical-stimulus-free built-in-self-test (BIST) integrated circuit (IC) design characterizing the sensitivity of capacitive MEMS accelerometers is presented. The BIST circuity can extract the amplitude and phase response of the acceleration sensor's mechanics under electrical excitation within 0.55% of error with respect to its mechanical sensitivity under the physical stimulus. Sensitivity characterization is performed using a low computation complexity multivariate linear regression model. The BIST circuitry maximizes the use of existing analog and mixed-signal readout signal chain and the host processor core, without the need for computationally expensive Fast Fourier Transform (FFT)-based approaches. The BIST IC is designed and fabricated using the 0.18-µm CMOS technology. The sensor analog front-end and BIST circuitry are integrated with a three-axis, low-g capacitive MEMS accelerometer in a single hermetically sealed package. The BIST circuitry occupies 0.3 mm2 with a total readout IC area of 1.0 mm2 and consumes 8.9 mW during self-test operation.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2017
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Heng-YuChiu and 邱恒伃. "Design of a Single-Axis Capacitive Accelerometer with AC Offset Cancellation Circuit." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/u3635g.
Full textAbstract:
碩士國立成功大學
電腦與通信工程研究所
107
Owing to the recent trend of fewer children and more elders in Taiwan, we might face the shortage of the medical personnel in the future. One of the solutions is to combine high technologies, such as wearable devices, telemedicine, and cloud computing, with hospitals, so that it can lessen the burden on caregivers. In order to apply the accelerometer to wearable devices, a single-axis capacitive accelerometer system has been implemented, whose sensor is made by micro-electromechanical system (MEMS) process. The capacitor bridge outputs are reset to dc voltage regularly for reducing the bias voltage drift caused by the undesirable charging and discharging from the capacitive accelerometer. Besides, an ac offset cancellation loop is proposed to suppress the offset voltage originated from the mismatches in the MEMS sensor, so the mismatch-induced offset would not saturate the chip output. The integration of the MEMS sensor and the complementary metal-oxide-semiconductor (CMOS) circuits significantly reduces the instrument size and costs. The proposed chip, fabricated by Taiwan Semiconductor Manufacturing Company (TSMC) 0.35μm 2P4M mixed-signal standard CMOS process and MEMS post process, consists of the front-end sensor and the back-end signal processing circuits, and it occupies 2.429×2.068-mm2 area. The measured sensitivity is 69.11(mVpp/g) within the ±8g sensing range, and the power consumption of the chip is 1.89mW with a 3.3V power supply.
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Chen, Jiun-Cheng, and 陳俊成. "The Design, Analysis and Simulation of Capacitive Micro-Accelerometer System and Sensing Circuit." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/14106462106668279365.
Full textAbstract:
碩士國立交通大學
電機與控制工程系
90
The present dissertation studies the system architecture and sensing circuits of a capacitive micro-accelerometer. Sigma-delta concept is used as the system architecture of micro-accelerometer for the purpose of high S/N ratio, digital output and closed-loop electrostatic feedback. Furthermore, by reducing damping coefficient or increasing spring coefficient and proof mass, we are able to produce high quality factor. By using vacuum packaging, we can further reduce Brownian noise. Note that when reducing the effects of these noises, the remaining noises compared to circuit noise can be neglected. Two common used circuits are analyzed in the sensing circuit with the presence of the non-ideal characteristics of the circuits. By performing a series of analysis, we have used a modified version of corrected double sampling to reduce non-ideal circuit characteristic except thermal noise. In order to increase sensing resolution, we performed the optimization to the Op amp thermal noise. Finally, we are able to develop a capacitive micro-accelerometer system model for the purpose of simulating the dynamic behavior. Note that with the model, we are able to compare different systems by tuning its corresponding parameters. Here, we verified that the analysis result is closed to the theory. For the switch capacitor circuit, due to the switch error effect, the result has experienced a 5% difference than theory. An operational amplifier with a 57M Hz unit-gain bandwidth, and a 204K Hz frequency of oscillator and a clock generator were designed and verified. The object of this dissertation is to design a ±5g input which has a ±5v output voltage. The simulation result show that at 100K Hz sampling frequency, the system possesses correct output signal when input signal is in the range of ±4.7g, and the output signal has a 0.1v maximum error.
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Wu, Po-Chi, and 吳柏奇. "A CMOS-MEMS Capacitive Accelerometer with Differential LC-tank Oscillator and Digital Output." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/776vk5.
Full textAbstract:
碩士國立交通大學
電控工程研究所
101
The rapid development of electronics products makes the entire semiconductor technology continue to progress. More and more mobile devices need various sensors, leading to the growing demand for MEMS sensors. The MEMS sensors whose fabrication process is compatible to the standard CMOS process are called CMOS MEMS sensors. The CMOS MEMS sensors have the advantages of low cost and high performance. This thesis used TSMC 0.18μm standard CMOS process and post process supported by National Chip Implementation Center to complete a CMOS MEMS accelerometer. This accelerometer has capacitive sensing mechanism, and integrates the sensing capacitor with an oscillator circuit and the back-end circuit to have a frequency and digital output. The oscillation frequency can be influenced by the sensing capacitor. By detecting the variation of the oscillator output frequency, this accelerometer can define the acceleration value applied on this chip. The combination of capacitive sensing and frequency output has the advantage of capacitor values being less sensitive to temperature, post process being relatively simple, no need of complex analog-digital converters and higher sensitivity and linearity. The measurement result shows that this accelerometer can achieve 3.44 MHz/g sensitivity and 0.4mg/rtHz resolution.
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Wu, Chao-Hsuan, and 吳兆軒. "The Design, Simulation and Fabrication of CMOS Sensing Circuits of Capacitive Micro Accelerometer." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/87017797269993789778.
Full textAbstract:
碩士國立交通大學
電機與控制工程系
91
The purpose of this dissertation is to discuss the structure and implementation of CMOS sensing circuits of capacitive micro accelerometer. First, the structure of micro accelerometer will be analyzed. Then we will introduce the synchronous detection and switched-capacitor sensing schemes which are both widely used in capacitive sensing circuits. As a result of the various sources of noises, however, these two sensing schemes will not be suitable for sensing which is in the range of hundreds or even tens of femto-farads. Therefore, the CDS sensing scheme which has higher signal-to-noise ratio is used in this thiese. From the post-simulation results which uses UMC 0.5 2P2M process, the outputs have quite high linearity and sensitivity. The resolution is up to 0.5fF. Moreover, we also use the discrete electronic elements to implement and verify the CDS sensing circuits.
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"An Electrical Stimulus based Built In Self Test (BIST) circuit for Capacitive MEMS accelerometer." Master's thesis, 2013. http://hdl.handle.net/2286/R.I.18677.
Full textAbstract:
abstract: Micro Electro Mechanical Systems (MEMS) is one of the fastest growing field in silicon industry. Low cost production is key for any company to improve their market share. MEMS testing is challenging since input to test a MEMS device require physical stimulus like acceleration, pressure etc. Also, MEMS device vary with process and requires calibration to make them reliable. This increases test cost and testing time. This challenge can be overcome by combining electrical stimulus based testing along with statistical analysis on MEMS response for electrical stimulus and also limited physical stimulus response data. This thesis proposes electrical stimulus based built in self test(BIST) which can be used to get MEMS data and later this data can be used for statistical analysis. A capacitive MEMS accelerometer is considered to test this BIST approach. This BIST circuit overhead is less and utilizes most of the standard readout circuit. This thesis discusses accelerometer response for electrical stimulus and BIST architecture. As a part of this BIST circuit, a second order sigma delta modulator has been designed. This modulator has a sampling frequency of 1MHz and bandwidth of 6KHz. SNDR of 60dB is achieved with 1Vpp differential input signal and 3.3V supplyDissertation/Thesis
M.S. Electrical Engineering 2013
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Oliveira, Joaquim José Silva Faria. "Complement the touch information given by the smartphone's capacitive screens with the information received by the accelerometer and gyroscope." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/73700.
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Currently it only is possible to obtain information about a tap on the smartphone's screen using the touch sensor. The goal of this project is to complement the information given by the smartphones touch screen with information given by the accelerometer and gyroscope and this way to extend the smartphone's touch capabilities with data such as tap strength, smartphone's holding position while taping (if it is on the users hands or laying on a hard surface) or which finger the touch was performed (thumb or index finger). Using sensors to detect touches is not a new idea, as there is already research which use the smartphone accelerometer to infer which keystrokes were made on a touch screen, and use the accelerometer information to know when there was a tap on the virtual keybord is made even before the touchscreen detects it, this project aims to use this information to other proposes, getting new information on a touch event and process that information in order to be useful to the user or developer party.Currently smartphones are the consumer electronic devices with higher growth rate. The wide variety of functionalities that they provide is what makes them so desirable. We can use them to play, to communicate, to take pictures, to guide us, to work, and more. For that to be possible the smartphones have several built-in sensors, which make them much more interesting.This project amis to use smartphone embeded sensors to complement the information given by the smartphones touch screen with information given by the accelerometer and gyroscope. In others words, using sensors like the accelerometers and gyroscopes,to provide new ways to characterize the touch. For that the accelerometer and gyroscope signals will be studied and several algorithms will be create, such as to detect touches using this two sensors, to determine the device position (hand or on surface), the hand and the finger used to touch on device and the touch force.
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Oliveira, Joaquim José Silva Faria. "Complement the touch information given by the smartphone's capacitive screens with the information received by the accelerometer and gyroscope." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/73700.
Full textAbstract:
Currently it only is possible to obtain information about a tap on the smartphone's screen using the touch sensor. The goal of this project is to complement the information given by the smartphones touch screen with information given by the accelerometer and gyroscope and this way to extend the smartphone's touch capabilities with data such as tap strength, smartphone's holding position while taping (if it is on the users hands or laying on a hard surface) or which finger the touch was performed (thumb or index finger). Using sensors to detect touches is not a new idea, as there is already research which use the smartphone accelerometer to infer which keystrokes were made on a touch screen, and use the accelerometer information to know when there was a tap on the virtual keybord is made even before the touchscreen detects it, this project aims to use this information to other proposes, getting new information on a touch event and process that information in order to be useful to the user or developer party.Currently smartphones are the consumer electronic devices with higher growth rate. The wide variety of functionalities that they provide is what makes them so desirable. We can use them to play, to communicate, to take pictures, to guide us, to work, and more. For that to be possible the smartphones have several built-in sensors, which make them much more interesting.This project amis to use smartphone embeded sensors to complement the information given by the smartphones touch screen with information given by the accelerometer and gyroscope. In others words, using sensors like the accelerometers and gyroscopes,to provide new ways to characterize the touch. For that the accelerometer and gyroscope signals will be studied and several algorithms will be create, such as to detect touches using this two sensors, to determine the device position (hand or on surface), the hand and the finger used to touch on device and the touch force.
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Khan, Sambuddha. "Development Of Micromachined And Meso-Scale Multi-Axis Accelerometers With Displacement-Amplifying Compliant Mechanisms." Thesis, 2013. http://hdl.handle.net/2005/2602.
Full textAbstract:
Simultaneously achieving high-sensitivity and a large resonance frequency of micromachined accelerometers is difficult because of the inherent trade-off between the two. In this thesis, we present a mechanical displacement-amplifying technique that is amenable to micromachining to enhance sensitivity without compromising on the resonance frequency and cross-axis sensitivity. Depending on the requirements of sensitivity alone or sensitivity and resonance frequency, Displacement-amplifying Compliant Mechanisms (DaCMs) are designed using the selection map-based technique, which indicates the limits of what is possible for given specifications on size and microfabrication.
In order to prove the benefits of a DaCM, we modified the designs of two very sensitive capacitive micromachined accelerometers from the literature by incorporating DaCMs and showed that, within the same footprint on the chip, the displacement sensitivity could be enhanced by more than 60% while the resonance frequency was also improved by more than 30%. As the focus of the thesis is to explore the integration of DaCMs into accelerometers, the analytical, computational, and practical aspects are discussed in detail. Both single and dual axis in-plane accelerometers are considered. The fabrication processes used are Silicon-on-Insulator Multi-user MEMS Processes (SOIMUMPs) and a customized Silicon-on-Insulator (SOI) based process. The fabricated accelerometers are packaged and brought to the product form. They were tested at the die level as well as in the packaged form.
Under dynamic conditions, the measured amplification factor of the fabricated single-axis in-plane accelerometer was observed to be 11. The overall dimension of the accelerometer was 4.25 mm × 1.25 mm. The first in-plane natural frequency of the fabricated accelerometer was found to be 6.25 kHz. The voltage sensitivity of the packaged accelerometer with the DaCM measured 26.7 mV/g at 40 Hz with differential capacitance sensitivity of 3926 ppm/g around the base capacitance of 0.75 pF.
The fabricated dual-axis accelerometer has a special configuration of twelve folded-beam suspension blocks that de-couple any displacements along the two in-plane orthogonal axes. The decoupling feature is retained even after adding the DaCMs along both the axes. The total device size was 8.6 mm × 8.6 mm. The device was also fabricated and packaged inside a ceramic flat-pin package using hybrid die-to-die wire-bonding. Die-level dynamic characterization showed that the average geometric advantage achieved using the DaCMs is 6.2 along both the in-plane axes. The measured axial voltage sensitivity of about 580 mV/g for both the axes was achieved with a cross-axial sensitivity of less than 2% and a natural frequency of 920 Hz. The static capacitance sensitivity was found to be 0.296 × 106 ppm/g with a base capacitance of 0.977 pF. Also presented in this work is a wide-band dual-axis accelerometer without an amplifying mechanism. Its first two in-plane modal frequencies measured 14.2 kHz. The measured sensitivity of the packaged accelerometer along both the axes of the device was found to be 62 mV/g at 200 Hz.
Aiming at towards cost-effective accelerometers for small-volume markets, we also developed a single-axis and two dual-axis meso-scale spring-steel in-plane accelerometers equipped with Allegro A1395 linear Hall-effect sensors for sensing the displacement of the proof-mass. The single-axis in-plane meso-scale accelerometer also contains a DaCM. It is observed through simulation that the single-axis design with a DaCM is 39% more sensitive and has 41% more bandwidth compared to a single-axis design without a DaCM. The measured sensitivity of the fabricated single-axis spring-steel accelerometer with a DaCM was found to be 71.4 mV/g with a minimum resolvable acceleration of 14 milli-g. The unique features of the first generation of dual-axis accelerometers are that a rechargeable Li-ion battery adds to the proof-mass. It also contains a de-coupling mechanism that can decompose any planar acceleration into its axial components. The second generation of dual-axis accelerometers is more compact in size. All the mechanical elements of the accelerometers are made of EN J42/AISI 1080 spring steel foil machined using Wire-cut Electro-Discharge- Machining. The measured sensitivity of the first generation of dual-axis meso-scale accelerometers is 78 and 108 mV/g along the X and Y axes whereas the second generation device exhibits a sensitivity of 40 mV/g for both the axes. The thesis concludes that the sensitivity of a displacement-based sensor can be improved using a suitably designed DaCM without compromising the resonance frequency and hence the bandwidth. Furthermore, the work describing the development of meso-scale accelerometers also establishes spring steel as a viable material for meso-scale applications.
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Yueh-Kang, Lee, and 李岳剛. "Development of CMOS-MEMS Capacitive Accelerometers." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/93991980748155628450.
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Farahani, Hamed. "Design and fabrication of micromachined capacitive accelerometers." 2009. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=958054&T=F.
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Huang, Meng-Ju, and 黃盟珠. "The signal processing circuit for capacitive accelerometers." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/44821293957729813162.
Full textAbstract:
碩士國立臺灣大學
電機工程學系研究所
86
In this thesis, we are devoted to the research of the signal processing circuits used in the capacitive sensor system. We discuss the analysis of the system structure, the processing of sensor signal, and the design of the readout circuits. The readout circuits for capacitive accelerometer have also been designed and tested.
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Fu, Chih-Chang, and 傅至璋. "Micro Accelerometers with a Hybrid Piezoresistive/Capacitive Sensing Mechanism." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/68222897420975713910.
Full textAbstract:
碩士國立臺灣大學
光電工程學研究所
96
In this paper, we want to introduce a novel micro accelerometer with a hybrid piezoresistive/capacitive sensing technique. In general, micro accelerometer has only one type sensing technique. In this paper, we report, to the best of our knowledge, the first micro accelerometer using a hybrid capacitive/piezoresistive sensing technique. Here, we will introduce two micro accelerometer, in-plane and out-of-plane, designed by us. For our novel high-g in-plane micro accelerometer, the measured capacitance change in the capacitive sensing mode is 0.028 pF under 690 g. The measured voltage change in the piezoresistive sensing mode is 0.335 V under 612 g. The mechanical resonant frequency of the micro accelerometer is measured to be 4.26 kHz, i.e. < 5% deviation from the ANSYS prediction. For our z-axis out-of-plane, the maximum measured voltage change in the piezoresistive sensing mode is 0.215V under 11 g. The maximum measured capacitance change in the capacitive sensing mode is 0.26 pF under 10.3 g. The mechanical resonant frequency of the micro accelerometer is calculated to be 353 Hz.
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Fu, Chih-Chang. "Micro Accelerometers with a Hybrid Piezoresistive/Capacitive Sensing Mechanism." 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2607200813350800.
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王鑫得. "Modeling and Control of a Capacitative Semiconductor Accelerometer." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/75014550477928035760.
Full textAbstract:
碩士國立中正大學
機械工程研究所
86
This thesis studies the dynamics and performance of a capacitative micro - accelerometer with PD control under three different signal processing methods, namely modulation - demodulation method, pulse Whdth Modulation (PWM) method and Phase Locked Loops (PLL) method. Based on the performance requirements of the accelerometer system, we obtain a set of beeter - tuned PD control parameter for each signal processing method by numerical simulations. Finally, the advantages and disadvantages for the present system of the three signal processing approaches are discussed throgh the analysis of system''s time responses, bode plots, the input output relationships, and noise rejection ability. An optimal signal signal processing control structure is then proposed for our micro - accelerometer.
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Huang, Hsu-Jung, and 黃旭榕. "Systematic Design of PD Controller for Capacitive Semi-Conductive Accelerometers." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/41469819608429724336.
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碩士國立中正大學
機械系
87
The systematic design of PD controllers for capacitive semi-conductive accelerometers(CSCA) is studied in the thesis. Due to the modulation-demodulation of the output signal of the microaccelerometer, the overall system is linear time- varying. Two approaches are taken in this study to design PD controller for this linear time-varying system. First, we design the parameters of the PD controller by conventional Floquet theory to achieve the internal stability of the CSCA system, and the results are confirmed by numerical simulations. The experiment based on an equivalent CSCA model is conducted to verify the feasibility of the method. On the other hand, two previous methods are integrated to propose a systematic design method for PD controllers of multi-output LTV systems. Similar to the feedback linearization technique, the proposed method cancels the time-varying terms by feedback and Lyapunov coordinate transformation. The existence of solu- tions and robustness of the PD controllers are also discussed. Finally, it is applied to the multi-output LTV CSCA system.