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Journal articles on the topic 'SiGe HBT model'

Author: Grafiati

Published: 3 June 2025

Last updated: 19 July 2025

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1

Hu Hui-Yong, Zhang He-Ming, Lyu Yi, et al. "SiGe HBT large signal equivalent circuit model." Acta Physica Sinica 55, no. 1 (2006): 403. http://dx.doi.org/10.7498/aps.55.403.

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2

Bo, Han, Li Shoulin, Cheng Jiali, Yin Qiuyan, and Gao Jianjun. "MEXTRAM model based SiGe HBT large-signal modeling." Journal of Semiconductors 31, no. 10 (2010): 104004. http://dx.doi.org/10.1088/1674-4926/31/10/104004.

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3

S., M.Moududul Islam, Arafat Yeasir, Ziaur Rahman Khan Md., and Bahar Chowdhury Md.Iqbal. "Base Transit Time Modeling of Gaussian-Doped SiGe HBT Considering Field-Dependence of Mobility." International Journal of Research in Electronics and Computer Engineering (IJRECE) 4, no. 1 (2016): 53–59. https://doi.org/10.5281/zenodo.14702660.

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This work assesses the effects of fielddependence of the carrier mobility on the base transit time of an npn SiGe hetero-junction bipolar transistor (HBT) with its base heavily doped with Gaussian type doping profile. Three types of Ge dosing, namely, box, trapezoidal and triangular profiles of SiGe HBT is represented by a generalized trapezoidal Ge-dosing profile. An analytical model has been developed considering this field-dependence. The model also includes the various effects caused by the non-uniformity of the base doping profile and also, of the Ge-content in the base. The model applicability has been extended from the lowinjection level to the moderate-injection level by applying the concept of perturbation theory. The simulation results of the developed model show that the field-dependence of the carrier mobility increases the base transit time considerably. This increase in the transit time is found higher in the SiGe HBTs in comparison with the Si BJTs (no Ge dosing). Among the three Ge dosing profiles of Gaussian doped SiGe HBT, this increase is observed as the highest for triangular one under all level of injections. Model results also show that the increase in the transit time decreases as the peak Ge-fraction increases for a triangular Ge-dosing profile and of uniform, exponential and Gaussian base doping profiles, this increase is found the largest for Gaussian one. All these results are, therefore, crucial for designing low transit time and corresponding high frequency SiGe-HBT design. 

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4

Chowdhury, Md. Iqbal Bahar. "Base Transit Time Modeling of Gaussian-Doped SiGe HBT Considering Field-Dependence of Mobility." INTERNATIONAL JOURNAL OF RESEARCH IN ELECTRONICS AND COMPUTER ENGINEERING 4, no. 1 (2016): 53–59. https://doi.org/10.5281/zenodo.15315518.

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This work assesses the effects of fielddependence of the carrier mobility on the base transit time of an npn SiGe hetero-junction bipolar transistor (HBT) with its base heavily doped with Gaussian type doping profile. Three types of Ge dosing, namely, box, trapezoidal and triangular profiles of SiGe HBT is represented by a generalized trapezoidal Ge-dosing profile. An analytical model has been developed considering this field-dependence. The model also includes the various effects caused by the non-uniformity of the base doping profile and also, of the Ge-content in the base. The model applicability has been extended from the lowinjection level to the moderate-injection level by applying the concept of perturbation theory. The simulation results of the developed model show that the field-dependence of the carrier mobility increases the base transit time considerably. This increase in the transit time is found higher in the SiGe HBTs in comparison with the Si BJTs (no Ge dosing). Among the three Ge dosing profiles of Gaussian doped SiGe HBT, this increase is observed as the highest for triangular one under all level of injections. Model results also show that the increase in the transit time decreases as the peak Ge-fraction increases for a triangular Ge-dosing profile and of uniform, exponential and Gaussian base doping profiles, this increase is found the largest for Gaussian one. All these results are, therefore, crucial for designing low transit time and corresponding high frequency SiGe-HBT design.     

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5

Li, Yao, Deyi Kong, Jiang Zhen, and Juyan Xu. "A base transport model for ultra-thin-base SiGe HBT." International Journal of Electronics 87, no. 11 (2000): 1281–87. http://dx.doi.org/10.1080/002072100750000097.

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6

Fregonese, S., G. Avenier, C. Maneux, A. Chantre, and T. Zimmer. "A compact model for SiGe HBT on thin-film SOI." IEEE Transactions on Electron Devices 53, no. 2 (2006): 296–303. http://dx.doi.org/10.1109/ted.2005.862237.

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7

Saha, Bishwadeep, Sebastien Fregonese, Anjan Chakravorty, Soumya Ranjan Panda, and Thomas Zimmer. "Sub-THz and THz SiGe HBT Electrical Compact Modeling." Electronics 10, no. 12 (2021): 1397. http://dx.doi.org/10.3390/electronics10121397.

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From the perspectives of characterized data, calibrated TCAD simulations and compact modeling, we present a deeper investigation of the very high frequency behavior of state-of-the-art sub-THz silicon germanium heterojunction bipolar transistors (SiGe HBTs) fabricated with 55-nm BiCMOS process technology from STMicroelectronics. The TCAD simulation platform is appropriately calibrated with the measurements in order to aid the extraction of a few selected high-frequency (HF) parameters of the state-of-the-art compact model HICUM, which are otherwise difficult to extract from traditionally prepared test-structures. Physics-based strategies of extracting the HF parameters are elaborately presented followed by a sensitivity study to see the effects of the variations of HF parameters on certain frequency-dependent characteristics until 500 GHz. Finally, the deployed HICUM model is evaluated against the measured s-parameters of the investigated SiGe HBT until 500 GHz.

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8

Hui-Yong, Hu, Zhang He-Ming, Dai Xian-Ying, et al. "Model of transit time for SiGe HBT collector junction depletion-layer." Chinese Physics 14, no. 7 (2005): 1439–43. http://dx.doi.org/10.1088/1009-1963/14/7/030.

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9

Zaręba, Agnieszka, Lidia Łukasiak, and Andrzej Jakubowski. "Modeling of the inverse base width modulation effect in HBT transistor with graded SiGe base." Journal of Telecommunications and Information Technology, no. 3 (June 25, 2023): 88–92. http://dx.doi.org/10.26636/jtit.2007.3.836.

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A model of the position of the edge of emitter-base junction in the base and collector current pre-exponential ideality factor in HBT transistor with a SiGe base is presented. The model is valid for transistors with nonuniform profiles of doping and Ge content. The importance of taking into account the dependence of the effective density of states in SiGe on local Ge content and that of electron diffusion coefficient in SiGe on drift field for modeling accuracy is studied.

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10

Niu, Guofu, Yiao Li, Huaiyuan Zhang, Andries Scholten, and Marnix Willemsen. "Avalanche Modeling in Mextram 505 and Implications on Circuit Simulations." ECS Transactions 109, no. 4 (2022): 179–88. http://dx.doi.org/10.1149/10904.0179ecst.

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This paper presents recent advances in compact modeling of avalanche multiplication in Mextram 505, an industry-standard transistor model, including new model features, improved model implementations, and implications for SiGe HBT RF circuit simulation and device modeling.

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11

Gupta, Dinesh, and Kaushik Nayak. "Silicon-Germanium Heterojunction Bipolar Transistor DC and AC Analysis Operating under Cryogenic Temperature." Electronics 11, no. 24 (2022): 4164. http://dx.doi.org/10.3390/electronics11244164.

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In this work, the numerical simulation of a SiGe heterojunction bipolar transistor (HBT) for DC and AC performance operating at cryogenic temperature with a hydrodynamic carrier transport model is analyzed. A new modified temperature-dependent Si1−xGex energy bandgap model was used. Using a simplified 2D TCAD design structure, the device characteristics on 55 nm SiGe HBT technology and the mobility model are calibrated with experimental data. Base current reversal due to induced impact-ionization at the collector-base junction is analyzed, where the estimated collector-emitter breakdown voltage with the base open (BVCEO) is 1.48 V at 300 K. This reveals good voltage handling ability. At cryogenic temperatures, dopant incomplete ionization in the lightly doped collector region shows a 28% decrease in ionized dopant concentration at 50 K; this affects the base-collector depletion capacitance. The emitter electron barrier tunneling leakage on collector current is studied using a non-local e-barrier tunneling model at different temperatures that shows an improvement in peak DC gain at lower temperatures. Using the small-signal ac analysis, the cut-off frequency and the maximum oscillation frequency are extracted for high-frequency application, and the base widening effect is discussed. A comparison of this work with measured data on 90 nm SiGe HBT is also discussed in brief, which shows improvements in the simulated structure.

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12

Xu, Xiao Bo, He Ming Zhang, Hui Yong Hu, Shan Shan Qin, and Jiang Tao Qu. "Collector Resistance of Accumulation-Subcollector Transistors for SOI SiGe BiCMOS Technology." Applied Mechanics and Materials 110-116 (October 2011): 5452–56. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.5452.

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An analytical expression for collector resistance of a novel vertical SiGe partially-depleted accumulation-subcollector HBT on thin SOI is obtained. Supported by simulation result, the resistance decreases quickly with the increase of substrate-collector bias and improves the transit frequency dramatically. The model is found to be significant in the design and simulation of 0.13 μm millimeter wave SiGe SOI BiCMOS technology.

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13

Sun, Ya-Bin, Jun Fu, Yu-Dong Wang, Wei Zhou, Wei Zhang, and Zhi-Hong Liu. "Extraction of temperature dependences of small-signal model parameters in SiGe HBT HICUM model." Chinese Physics B 25, no. 4 (2016): 048501. http://dx.doi.org/10.1088/1674-1056/25/4/048501.

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14

Sun, Yabin, Ziyu Liu, Xiaojin Li, and Yanling Shi. "Distributed Small-Signal Equivalent Circuit Model and Parameter Extraction for SiGe HBT." IEEE Access 7 (2019): 5865–73. http://dx.doi.org/10.1109/access.2018.2879972.

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15

Sokolic, S., B. Ferk, and S. Amon. "SiGe HBT simulation based on mp* (T, NA, xGE) numerical model HEM." Le Journal de Physique IV 08, PR3 (1998): Pr3–117—Pr3–120. http://dx.doi.org/10.1051/jp4:1998327.

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16

Lee, Chie-In, Yan-Ting Lin, Bo-Rung Su, and Wei-Cheng Lin. "SiGe HBT Large-Signal Table-Based Model With the Avalanche Breakdown Effect Considered." IEEE Transactions on Electron Devices 62, no. 1 (2015): 75–82. http://dx.doi.org/10.1109/ted.2014.2373057.

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17

Xu Xiao-Bo, Zhang He-Ming, Hu Hui-Yong, Xu Li-Jun, and Ma Jian-Li. "A collector space charge region model for SiGe HBT on thin-film SOI." Acta Physica Sinica 60, no. 7 (2011): 078502. http://dx.doi.org/10.7498/aps.60.078502.

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18

Zhang, Anni, Guofu Niu, Yiao Li, Marnix Willemsen, and Andries Scholten. "Improved Nonlinear Self-Heating Compact Modeling in SiGe HBTs Using Mextram." ECS Transactions 114, no. 2 (2024): 83–91. http://dx.doi.org/10.1149/11402.0083ecst.

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The linear and nonlinear SH models in the latest versions of Mextram are evaluated, with an emphasis on high-power biases and ambient temperature scalability. The Mextram nonlinear SH model is shown to have limitations in fitting high-power regions at all temperatures. An investigation of the dynamic thermal resistance rTH reveals that it is only a function of Tjunc, which limits the fitting capability of the current nonlinear SH model. A new nonlinear SH model is proposed based on analysis of the rTH characteristics to improve high-power region fitting at multiple ambient temperatures. The model is demonstrated on a SiGe HBT from −25◦C to 125◦C.

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19

Pellish, Jonathan A., Robert A. Reed, Akil K. Sutton, et al. "A Generalized SiGe HBT Single-Event Effects Model for On-Orbit Event Rate Calculations." IEEE Transactions on Nuclear Science 54, no. 6 (2007): 2322–29. http://dx.doi.org/10.1109/tns.2007.909987.

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20

Lu, T. C., and J. B. Kuo. "An analytical SiGe-base HBT model and its effects on a BICMOS inverter circuit." IEEE Transactions on Electron Devices 41, no. 2 (1994): 272–76. http://dx.doi.org/10.1109/16.277366.

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21

Saleh, Alaa, Abdel Kader El Rafei, Mountakha Dieng, et al. "Compact RF non-linear electro thermal model of SiGe HBT for the design of broadband ADC's." International Journal of Microwave and Wireless Technologies 4, no. 6 (2012): 569–78. http://dx.doi.org/10.1017/s1759078712000566.

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The design of high speed integrated circuits heavily relies on circuit simulation and requires compact transistor models. This paper presents a non-linear electro-thermal model of SiGe heterojunction-bipolar transistor (HBT). The non-linear model presented in this paper uses a hybrid π topology and it is extracted using IV and S-parameter measurements. The thermal sub-circuit is extracted using low-frequency S-parameter measurements. The model extraction procedure is described in detail. It is applied here to the modeling of npn SiGe HBTs. The proposed non-linear electro-thermal model is expected to be used for the design of high-speed electronic functions such as broadband analog digital converters in which both electrical and thermal aspects are engaged. The main focus and contribution of this paper stands in the fact that the proposed non-linear model covers wideband-frequency range (up to 65 GHz).

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22

Islam, Muhammad Johirul, and Md Iqbal Bahar Chowdhury. "Recombination Effects on Base Transit Time in Exponentially-Doped SiGe Heterojunction Bipolar Transistor (HBT): An Analytical Approach." Journal of Engineering and Exact Sciences 11, no. 1 (2025): 21464. https://doi.org/10.18540/jcecvl11iss1pp21464.

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In conventional models of base transit time in SiGe HBTs, the recombination in the base is usually neglected because the base is considered very thin to justify simplifications in the numerical calculation. Indeed, this assumption turns out not to be very valid at moderate injection levels, since carrier recombination could have important consequences for transistor performance. The paper presents an analytical model, which includes the recombination process in the exponentially doped base of SiGe HBTs operating under intermediate injection conditions. The inclusion of recombination makes the mathematical solution very complicated. In this work, an exponential approximation technique together with perturbation theory is applied, making it possible to solve the equations with a high degree of accuracy while reducing the mathematical complications. The model that is proposed clearly depicts that the recombination effects might play an important role in defining the base transit time of SiGe HBTs with a non-uniform doping profile. It also shows that any neglect of recombination could be seriously wrong, particularly in devices operating under an intermediate injection level. The insight obtained from the results of this study will lead to a deeper understanding of the behavior of SiGe HBT and its design and optimization for improved performance in various applications. A practical method developed herein is applied to the analysis of recombination effects with limited complication.

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23

Xu Xiao-Bo, Zhang He-Ming, and Hu Hui-Yong. "Improved base-collector depletion charge and capacitance model for SiGe HBT on thin-film SOI." Acta Physica Sinica 60, no. 11 (2011): 118501. http://dx.doi.org/10.7498/aps.60.118501.

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24

KUMAR, ARUN. "Relative Analysis of Speed and Noise Performance of SiGe HBT Between Experimental and Simulated Model." IOSR Journal of Electronics and Communication Engineering 1, no. 3 (2012): 18–27. http://dx.doi.org/10.9790/2834-0131827.

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25

d’Alessandro, Vincenzo, Antonio Pio Catalano, Ciro Scognamillo, et al. "A Critical Review of Techniques for the Experimental Extraction of the Thermal Resistance of Bipolar Transistors from DC Measurements—Part I: Thermometer-Based Approaches." Electronics 12, no. 16 (2023): 3471. http://dx.doi.org/10.3390/electronics12163471.

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This paper presents a critical and detailed overview of experimental techniques for the extraction of the thermal resistance of bipolar transistors from simple DC current/voltage measurements. More specifically, this study focuses on techniques based on a thermometer, i.e., the relation between the base-emitter voltage and the junction temperature. The theory behind the techniques is described with a unified and comprehensible nomenclature. Advantages, underlying approximations, and limitations of the methods are illustrated. The accuracy is assessed by emulating the DC measurements with PSPICE electrothermal simulations of a transistor model, applying the techniques to the simulated currents/voltages, and comparing the extracted thermal resistance data with the values obtained from the target formulation embedded in the transistor model. An InGaP/GaAs HBT and an Si/SiGe HBT for high-frequency applications are considered as case-studies.

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26

JUNGEMANN, CHRISTOPH, BURKHARD NEINHÜS, and BERND MEINERZHAGEN. "HYDRODYNAMIC MODELING OF RF NOISE FOR SILICON-BASED DEVICES." International Journal of High Speed Electronics and Systems 13, no. 03 (2003): 823–48. http://dx.doi.org/10.1142/s0129156403002046.

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A 2D hydrodynamic model based on modified Langevin forces for terminal current noise in the RF range is presented for Si and SiGe devices, where all transport and noise parameters are generated by full-band Monte Carlo simulations under bulk conditions and stored in lookup tables. Since these tables have to be built only once, the accuracy of the noise model is improved without increasing the CPU time compared to models based on analytical expressions for the parameters. The accuracy of the noise model is assessed by comparison with the Monte Carlo device model and good agreement of both models is found for diffusion and generation noise. The terminal current noise of a realistic SiGe HBT is investigated and it is found that hole diffusion noise has a strong impact on the collector current noise. The limitations of the thermodynamic model, a compact model for noise, are explored by comparison with the hydrodynamic model.

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27

Lee, Chie-In, Yan-Ting Lin, and Wei-Cheng Lin. "An Improved Noise Model for SiGe HBT With an Inductive Breakdown Network in the Avalanche Region." IEEE Transactions on Device and Materials Reliability 15, no. 4 (2015): 588–94. http://dx.doi.org/10.1109/tdmr.2015.2490084.

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28

Wei, JiaNan, Yang Li, WeiTao Yang, et al. "Proton-induced current transient in SiGe HBT and charge collection model based on Monte Carlo simulation." Science China Technological Sciences 63, no. 5 (2020): 851–58. http://dx.doi.org/10.1007/s11431-019-1474-x.

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29

Jungemann, C., B. Neinhüs, and B. Meinerzhagen. "Investigation of the Local Force Approximation in Numerical Device Simulation by Full-band Monte Carlo Simulation." VLSI Design 13, no. 1-4 (2001): 281–85. http://dx.doi.org/10.1155/2001/10378.

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The critical assumptions in the drift-diffusion model are the local force approximation and the use of the Einstein relation under nonequilibrium conditions. The validity of these two approximations is investigated by full-band Monte Carlo simulation for a SiGe-HBT. It is found that neither the local force approximation nor the Einstein relation holds. Even Einstein relations generalized with the local temperature fail under quasiballistic transport conditions, indicating that the energy transport and hydrodynamic approach are also problematic.

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30

Taher, H., D. Schreurs, R. Gillon, et al. "Detecting variations of small-signal equivalent-circuit model parameters in the Si/SiGe HBT process with ANN." International Journal of RF and Microwave Computer-Aided Engineering 15, no. 1 (2004): 102–8. http://dx.doi.org/10.1002/mmce.20056.

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31

Sun, Yabin, Jun Fu, Ji Yang, et al. "An Improved Small-Signal Model for SiGe HBT Under OFF-State, Derived From Distributed Network and Corresponding Model Parameter Extraction." IEEE Transactions on Microwave Theory and Techniques 63, no. 10 (2015): 3131–41. http://dx.doi.org/10.1109/tmtt.2015.2468211.

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32

d’Alessandro, Vincenzo, Antonio Pio Catalano, and Ciro Scognamillo. "A Critical Review of Techniques for the Experimental Extraction of the Thermal Resistance of Bipolar Transistors from DC Measurements—Part II: Approaches Based on Intersection Points." Electronics 14, no. 9 (2025): 1743. https://doi.org/10.3390/electronics14091743.

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This work constitutes Part II of a comprehensive three-part study critically reviewing techniques for the indirect extraction of the thermal resistance in bipolar transistors using simple DC current/voltage measurements. While Part I focused on thermometer-based methods, this study examines techniques that rely on intersection points between electrical characteristics. The accuracy of these methods is assessed by applying them to DC curves obtained through PSPICE simulations of an in-house transistor model incorporating nonlinear thermal effects, and comparing the extracted thermal resistance data with the thermal resistance formulation embedded in the model. An InGaP/GaAs HBT and a Si/SiGe HBT for high-frequency applications are considered as case-studies. The analysis highlights key drawbacks affecting the methods, including theoretical approximations and sensitivity to the selection of intersection points. Among the techniques examined, only one adequately accounts for the nonlinear thermal behavior, though its original formulation presents practical limitations. To tackle this problem, we propose an improved and refined version of the approach that offers enhanced accuracy at the cost of increased complexity.

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33

Lee, Chie-In, Yan-Ting Lin, and Wei-Cheng Lin. "An Improved VBIC Large-Signal Equivalent-Circuit Model for SiGe HBT With an Inductive Breakdown Network by $X$ -Parameters." IEEE Transactions on Microwave Theory and Techniques 63, no. 9 (2015): 2756–63. http://dx.doi.org/10.1109/tmtt.2015.2458313.

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34

Hong, G. B., and J. G. Fossum. "Implementation of nonlocal model for impact-ionization current in bipolar circuit simulation and application to SiGe HBT design optimization." IEEE Transactions on Electron Devices 42, no. 6 (1995): 1166–73. http://dx.doi.org/10.1109/16.387252.

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35

Taher, H., D. Schreurs, and B. Nauwelaers. "Extraction of small-signal equivalent circuit model parameters for Si/SiGe HBT using S-parameters measurements and one geometrical information." AEU - International Journal of Electronics and Communications 60, no. 8 (2006): 567–72. http://dx.doi.org/10.1016/j.aeue.2005.11.004.

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36

Kim, Taeyeong, Garam Kim, Moon-Kyu Cho, John D. Cressler, Jaeduk Han, and Ickhyun Song. "Investigation of Device- and Circuit-Level Reliability of Inverse-Mode Silicon-Germanium Heterojunction Bipolar Transistors." Sensors 24, no. 22 (2024): 7130. http://dx.doi.org/10.3390/s24227130.

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The reliability of inverse-mode silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) under dc stress and its potential impact on the performance of basic analog amplifiers are investigated. In order to properly reflect the stress effects in various circuit applications, the degradations under three different configurations (active bias, diode connection, and off state) were experimentally characterized with the stress voltages applied up to 3000 s for each case. Based on the changes in the Gummel response, the degradations in device parameters such as current gain (β), transconductance (gm), and base-to-emitter resistance (rπ) were extracted and compared with the forward-mode counterpart. In addition, with the use of a small-signal equivalent model of a SiGe HBT, simple single-stage analog amplifiers were simulated as representative examples and their circuit-level performance metrics including gain and bandwidth were studied to estimate degradation characteristics with accumulated stress. It was found that transimpedance gain decreases and operation bandwidth increases to different levels due to device degradation, whereas a voltage amplifier exhibited much less changes.

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37

Kim, Taeyeong, Gyungtae Ryu, Jongho Lee, et al. "Simple Modeling and Analysis of Total Ionizing Dose Effects on Radio-Frequency Low-Noise Amplifiers." Electronics 13, no. 8 (2024): 1445. http://dx.doi.org/10.3390/electronics13081445.

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In this study, the degradation characteristics of radio frequency (RF)-low-noise amplifiers (LNA) due to a total ionizing dose (TID) is investigated. As a device-under-test (DUT), sample LNAs were prepared using silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) as core elements. The LNA was based on a cascode stage with emitter degeneration for narrowband applications. By using a simplified small-signal model of a SiGe HBT, design equations such as gain, impedance matching, and noise figure (NF) were derived for analyzing TID-induced degradations in the circuit-level performance. To study radiation effects in circuits, the SiGe-RF-LNAs fabricated in a commercial 350 nm SiGe technology were exposed to 10-keV X-rays to a total ionizing dose of up to 3 Mrad(SiO2). The TID-induced performance changes of the LNA were modeled by applying degradation to device parameters. In the modeling process, new parameter values after irradiation were estimated based on information in the literature, without direct measurements of SiGe HBTs used in the LNA chip. As a result, the relative contributions of parameters on the circuit metrics were compared, identifying dominant parameters for degradation modeling. For the TID effects on input matching (S11) and NF, the base resistance (RB) and the base-to-emitter capacitance (Cπ) of the input transistor were mostly responsible, whereas the transconductances (gm) played a key role in the output matching (S22) and gain (S21). To validate the proposed approach, it has been applied to a different LNA in the literature and the modeling results predicted the TID-induced degradations within reasonable ranges.

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38

Li, Yiao, Guofu Niu, Andries Scholten, and Marnix Willemsen. "Compact Modeling of Base Current High Injection Effect in SiGe HBTs." ECS Meeting Abstracts MA2024-02, no. 32 (2024): 2316. https://doi.org/10.1149/ma2024-02322316mtgabs.

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In bipolar transistor compact modeling, the forward mode base current typically consists of three components: space-charge recombination, back injection into the emitter, and neutral-base-recombination (NBR). At medium and high base-emitter voltages (VBE), the emitter back injection and NBR components dominate, and both increase exponentially with VBE. Deviation from the ideal behavior occurs at high VBE due to parasitic base and emitter resistance or self-heating. However, in many SiGe HBTs, standard compact models fail to capture experimentally observed IB-VBE characteristics, where the base current (IB) exhibits a high injection behavior that is more evident at lower collector-base voltages (VCB), as shown in Fig. 1. The simulation is done with Mextram 505.2 with resistance and self-heating parameters already calibrated. At a relatively low VBE of 0.72 V, the measured IB starts to bend downward compared to its typical behavior shown by the model, causing the increase of beta with VBE from 0.72 to 0.82 V. Parameter optimization cannot possibly fit silicon data and a new base current model is called for. Similar behavior has been observed by other groups and attributed to carbon-induced NBR [1]-[3]. Interestingly, the onset of this IB high injection occurs at a lower VBE than the onset of collector current (IC) high injection, which is typically due to Kirk's effect or quasi-saturation effect. Such IB high injection behavior also exhibits a complex VCB dependence. The change of IB-VBE slope is less visible at higher VCB due to self-heating, which increases IB. We present a recently developed compact model of base current that models this high-injection effect. The foundation of the high-injection effect model is an analytical expression of the neutral base recombination rate applicable to all injection levels derived from SiGe HBT NBR physics. Based on experimental data measured on devices with different geometries, we model both the area component and peripheral component with separate temperature coefficients. The area component is subject to neutral base width modulation modeled by the same parameters used for the Early effect. A quasi-saturation-induced component is included to model the NBR after the electrical neutral base pushes out at high current densities. The quasi-saturation component has its dedicated parameters to account for the NBR at the SiGe-base/Si-substrate epitaxial growth interface discussed in [4] and [5]. This component comes into play at higher VBE. Fig. 2 demonstrates the new model's capability in capturing the measured IB high injection behavior and its complex VCB dependence, as well as the much-improved fitting of the beta vs. VBE characteristics. The inclusion of the NBR high-injection effect in the base current model enables more accurate modeling of SiGe HBTs. The model has been implemented in Mextram 505.3 and later versions [6]. References: [1] B. Barbalat, et al., Semicond. Sci. Technol., vol. 22, no. 1, pp. s99-102, 2007. [2] A. Ildefonso et al., IEEE Transactions on Nuclear Science, vol. 70, no. 8, pp. 1797-1804, Aug. 2023. [3] H. P. Lee et al., IEEE BCICTS, pp. 253-256, 2023. [4] G. Niu et al., IEEE TED, vol. 45, no. 12, pp. 2499-2504, 1998. [5] T. Takagi et al., IEEE BCTM, pp. 114-117, 2000. [6] G. Niu, Mextram 505.3, released 2022. Figure 1

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Zhang, Anni, Guofu Niu, Yiao Li, Marnix Willemsen, and Andries Scholten. "Improved Nonlinear Self-Heating Compact Modeling in SiGe HBTs Using Mextram." ECS Meeting Abstracts MA2024-02, no. 32 (2024): 2317. https://doi.org/10.1149/ma2024-02322317mtgabs.

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Accurate modeling of self-heating (SH) induced junction temperature rise is crucial for circuit design at high current densities required for high speed and high gain, as well as for reliability, as most degradations worsen at higher temperatures. For relatively lower power, the junction temperature rise (Trise) is typically modeled as a linear function of the dissipated power (Pdiss), with the slope being a parameter named thermal resistance (Rth), which can be further modeled as a function of ambient temperature (Tamb). In Mextram, this was the case until the recent implementation of the nonlinear SH model of [1]-[4] in Mextram 505.4 to improve modeling for high-power applications [5] [6]. A notable feature of the Mextram nonlinear SH model implementation is that it uses the same model parameters as its linear SH model, i.e., the low power Rth at reference temperature, rth, and the material thermal conductivity temperature coefficient ath used to describe the Tamb dependence of the linear SH Rth. In the nonlinear SH model, the same ath is used for Pdiss dependence of the effective Rth. Theoretically, if ath is already physical, one can simply turn on the nonlinear SH switch for improved modeling at higher collector current (IC) and collector-emitter voltage (VCE). The key to this simplicity lies in the specific form of the nonlinear functional dependence of Trise on Tamb and Pdiss derived by solving the nonlinear heat diffusion equation using the Kirchhoff transformation [7]. In practice, however, retuning these two parameters with high power data is beneficial for better overall fitting, particularly over multiple ambient temperatures. Fitting a larger power range at multiple ambient temperatures can still be challenging, due to the presence of multiple materials with different thermal conductivity temperature coefficients in the heat flow path and heat dissipation through multiple paths, e.g., from metallization in addition to substrate. To provide flexibility in silicon data fitting and extend the model's capability to a wider ambient temperature range and power range, we present an additional semi-empirical model. By deriving the slope of Trise versus Pdiss in the single material single path model problem, we show that it is only a function of the junction temperature Tjunc=Trise+Tamb, which is behind the ability of the model to use only two parameters for both Tamb and Pdiss variation. We propose a semi-empirical modification of the Trise versus Pdiss slope behavior, similar to the low-temperature CMOS measurement-based model in [8] and [9], which has the same issue of having a Tjunc-dependent Trise vs Pdiss slope, but an easier functional form for modification to provide flexibility in better fitting high power region over a wider range of ambient temperature. Our model construction ensures that the low Pdiss behavior is guaranteed to be the same as existing Mextram SH models. Figs. 1-3 show the modeling results of IC-VCE at various base-emitter voltages (VBEs) for a SiGe HBT at -25, 25, 75, and 125°C using 1) Mextram's default linear SH model; 2) Mextram 505.4's nonlinear SH model; and 3) the proposed wide power and temperature range nonlinear SH model. The new model shows the best overall fitting. In the full paper, we will also present results obtained using the nonlinear SH model used in HICUM L2 [10], where the effective Rth modeled as a linear or nonlinear function of Tjunc, and results obtained by implementing the model of [9]. We will make comparisons of the various models and provide best practice recommendations. [1] W. B. Joyce, SSE, vol. 18, pp. 321-322, 1975. [2] K. Poulton et al., JSSC, vol. 27, no. 10, pp. 1379-1387, 1992. [3] B. Yeats, Dig. GaAs IC symposium, pp. 59-62, 1999. [4] J. C. J. Paasschens et al., BCTM, pp. 96-99, 2004. [5] G. Niu et al., The Mextram Bipolar Transistor Model Version 505.4.0, 2023. [6] M. Willemsen, AKB-Workshop, 2023. [7] G. R. Kirchhoff, Vorlesungen über die Theorie der Wärme, 1894. [8] K. Triantopoulos et al., TED, vol. 66, no. 8, pp. 3498-3505, 2019. [9] G. Ghibaudo et al., SSE, vol. 192, article 108265, 2022. [10] M. Schroter, HICUM/L2 Technical documentation of model version 3.0.0, 2020. Figure 1

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Lyu Yi, Zhang He-Ming, Dai Xian-Ying, Hu Hui-Yong, and Shu Bin. "Junction capacitance models of SiGe HBT." Acta Physica Sinica 53, no. 9 (2004): 3239. http://dx.doi.org/10.7498/aps.53.3239.

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Niu, Guofu, Yiao Li, Huaiyuan Zhang, Andries Scholten, and Marnix Willemsen. "Avalanche Modeling in Mextram 505 and Implications on Circuit Simulations." ECS Meeting Abstracts MA2022-02, no. 32 (2022): 1202. http://dx.doi.org/10.1149/ma2022-02321202mtgabs.

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This paper presents several recent advances in compact modeling of avalanche multiplication in Mextram 505, an industry standard transistor model, including both new model features and improved model implementations. Implications of these improvements on circuit simulation are illustrated using RF SiGe HBTs. Feature wise, Mextram 505 adds a new physics-based model of the avalanche multiplication factor that accounts for the complex evolution of the epi-layer electric field at high current density, which can be activated with swavl=3. At a given collector-base bias VCB, the avalanche factor Gem is constant at low collector current density JC, starts to decrease when mobile electron density becomes comparable to epi-layer doping density due to charge compensation, and ultimately increases again when the base pushes out, and the electrical CB junction shifts to the epi-layer/buried layer interface. A parameter exavl can be used to turn on/off the rise of Gem at very high JC. An example of fitting IB versus IE for a common-base RF SiGe HBT at a fixed VCB=3V is given in Fig. 1. The measured base current is calculated from the difference of measured IE and IC, and hence shows some measurement noise. At low IE, Gem is constant, IB is linearly proportional to IE, with exavl=0, only the decrease of Gem with increasing JC is modeled, the IB bends upward at 0.05 A. With exavl=1, the rise of Gem at high JC is modeled, allowing the fitting of the downward bending of IB above 0.1 A. We will also discuss implications of such complex Gem behavior for RF linearity, particularly on the modeling of linearity sweet spots, i.e. biasing currents and voltages at which linearity peaks. Implementation wise, Mextram 505 uses the main current In as the initiating current in calculating the avalanche current Iavl, i.e. Iavl = In*Gem, as opposed to using the epi-layer current Ic1c2, i.e. Iavl = Ic1c2*Gem in Mextram 504. While for DC I-V, one can always use slightly different Gem model parameters to achieve the same degree of fitting, we found that the Mextram 504 approach can lead to unphysically high avalanche noise in voltage-controlled oscillator (VCO) circuits in some cases. Users should inspect the waveforms of Iavl as well as In to determine if this problem exists. The root problem is that the epi-layer current Ic1c2 also includes the CB junction capacitive charge current, which should not experience avalanche as the corresponding electron motion occurs outside the space charge region. While the Iavl error introduced has a small absolute value, the noise it introduces is often significant, and significantly increases oscillator phase noise. At the device level, this unphysical avalanche of capacitive charge current comes into play during modeling of the CB depletion capacitance, CCB, which is often extracted from off state y-parameter. Fig. 2 compares the CCB vs VCB simulated using In (505) and Ic1c2 (504) as avalanche initiating current, together with the CCB from measurement. The Gem value is shown on the right y-axis. When Gem approaches 1, the simulated CCB using Iavl = Ic1c2*Gem increases sharply, and becomes negative when Gem>1, a unphysical result users of Mextram 504 need to be aware of for high Gem biases. Using Iavl = In*Gem, as is in Mextram 505, the simulated CCB remains physical when Gem is high. An analytical model of such discrepancy has been developed using small signal frequency domain analysis and will be presented. In Mextram 504 and earlier versions of Mextram 505, Gem is limited to be less than 1 and then further limited through elegant considerations that ensure the collector current increases monotonically with the external VBE. Such limiting, however, cannot possibly work for the dynamic charge current which is the issue in the off-state CCB example as well as the VCO example above, due to how model equations are implemented in circuit simulators. One side effect of this Gem limiting is that avalanche induced runaway cannot be modeled for investigating safe operating area (SOA). A switch swgemlim is introduced in Mextram 505.3 to allow the users to turn off Gem limiting for such modeling, as shown in Fig. 3. The new avalanche model in Mextram 505 also enhances its ability to accurately predict the SOA boundary due to electrothermal runaway from the combined effects of avalanche and self-heating. Figure 1

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Friedrich, M., and H. M. Rein. "Analytical current-voltage relations for compact SiGe HBT models. I. The "idealized" HBT." IEEE Transactions on Electron Devices 46, no. 7 (1999): 1384–93. http://dx.doi.org/10.1109/16.772480.

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Humbert, Olivier, and Hans-Peter Kiem. "Long-Term Increase in Fetal Hemoglobin Expression in Nonhuman Primates Following Transplantation of Autologous Bcl11a Nuclease-Edited HSCs." Blood 126, no. 23 (2015): 2035. http://dx.doi.org/10.1182/blood.v126.23.2035.2035.

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Abstract Elevated levels of fetal hemoglobin (HbF) ameliorate the clinical symptoms of beta-thalassemia and sickle cell anemia. The transcription factor B-cell lymphoma/leukemia 11A (BCL11A) is required for silencing of gamma-globin expression in adult erythroid cells and functions as a switch from fetal to adult hemoglobin production in humans. BCL11A therefore constitutes a therapeutic target for the treatment of hemoglobinopathies. We inactivated BCL11A function by double-strand DNA break-induced mutagenesis using Transcription Activator-Like Effector Nucleases (TALENs). 20 to 30% gene editing could be achieved in vitro in human and nonhuman primate CD34+ cells by TALEN mRNAs electroporation targeting exon 2 of Bcl11a. Colony-forming efficiency was slightly lower in Bcl11a-edited CD34+ cells but lineage differentiation potential was unchanged. Erythroid differentiation of CD34+ cells in culture showed increased Fetal to Beta hemoglobin ratio in both human and primate Bcl11a-modified cells as compared to control cells, thus validating our editing approach to increase HbF production. To determine if Bcl11a-edited hematopoietic stem cells (HSCs) could be engrafted and give rise to HbF-producing erythrocytes, we transplanted a pigtail macaque with autologous CD34+ electroporated with Bcl11a TALEN mRNA following conditioning by total body irradiation. We detected about 1 % gene disruption in vivo early post-transplant and disruption frequency gradually declined to reach a set point of about 0.3% starting at day 28 post-transplantation. In this analysis, which we have so far taken out to 42 days, single clones could be tracked based on their mutation signature, and we found that several clones persisted over time, confirming engraftment of Bcl11a-modified cells. Since the transplantation procedure and chemo-radiotherapy conditioning can raise HbF production, three control animals that were transplanted using similar conditions as with the Bcl11a-edited HSCs and one untransplanted animal were also included in our analysis. Flow cytometry measurement of HbF in peripheral blood showed a rapid increase in F-cell production in all animals, reaching levels that ranged from 10% to 40% by 30 days, while the untransplanted control showed basal HbF expression of about 0.5% (Fig. 1A). The peak for HbF expression lasted for about 140 days and eventually returned to basal levels that averaged 0.5% for all control animals. In comparison, the animal transplanted with Bcl11a-edited cells showed significantly higher HbF levels starting at day 140 post-treatment (1-1.5%), and HbF production has remained constant for at least 150 days. This result was confirmed by hemoglobin mRNA analysis in peripheral blood using real-time PCR. We found a rapid increase in gamma globin expression following transplantation, before returning to near basal levels. As compared to controls, the animal transplanted with Bcl11a-edited cells showed a 5 to 10-fold increase in gamma to beta globin ratio at day 140 and this ratio has remained constant ever since (Fig. 1B). We are currently working on ways to enhance Bcl11a-editing and to select for Bcl11a-modified HSCs using targeted integration of the chemoselection cassette P140K MGMT to ultimately achieve curative HbF production. Potential TALEN off-target sites will also be examined as well as any side effect associated with the inactivation of BCL11A. Overall, our data demonstrate that transplantation of Bcl11a-edited HSCs results in elevated HbF production in nonhuman primates. Furthermore, we show that nonhuman primates can serve as a useful model for novel gene editing strategies toward the treatment of hemoglobinopathies. Figure 1. In vivo monitoring of HbF expression by flow cytometry and real-time PCR. (A) Intracellular HbF staining of peripheral blood measured by flow cytometry. (B) Real-time PCR analysis of hemoglobin transcripts in RNA isolated from peripheral blood. Expression was normalized to GAPDH and %HbG is calculated as HbG/(HbG+HbB). HbG=gamma globin; HbB=beta globin. Black line=Bcl11a transplant; grey line=control transplant; dashed line=untransplanted control. Figure 1. In vivo monitoring of HbF expression by flow cytometry and real-time PCR. (A) Intracellular HbF staining of peripheral blood measured by flow cytometry. (B) Real-time PCR analysis of hemoglobin transcripts in RNA isolated from peripheral blood. Expression was normalized to GAPDH and %HbG is calculated as HbG/(HbG+HbB). HbG=gamma globin; HbB=beta globin. Black line=Bcl11a transplant; grey line=control transplant; dashed line=untransplanted control. Disclosures No relevant conflicts of interest to declare.

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Ahmad, S., M. H. Lashari, and U. Farooq. "A preliminary study on devising a hematological formula for estimation of hemoglobin from packed cell volume in beetal goats." Arquivo Brasileiro de Medicina Veterinária e Zootecnia 74, no. 1 (2022): 77–82. http://dx.doi.org/10.1590/1678-4162-12568.

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ABSTRACT The study was devised with the aim to evaluate the relationship between hemoglobin (Hb) concentration and Packed Cell Volume (PCV) in beetal goats being reared under pastoralism. It also aims to devise a hematological formula for estimation of Hb from PCV. Female (n=59) and male goats (n=41) were bled for PCV determination through microhematocrit method, and Hb estimation through Sahli’s hemoglobinometer (HbD) as well as through calculation being 1/3rd of PCV (HbC). The HbD and HbC were statistically non-significant (P≥0.05) for male and female beetal goats. Overall, significantly (P≤0.01) positive correlation coefficient was noticed between HbD and PCV, and between HbD and HbC (r=0.75; adjusted r-square=0.57). As the overall model predicted that 57% variability in HbD could be deduced from PCV, hence, in order to enhance the prediction probability, the regression equation i.e. Hb concentration= 0.24(PCV) +1.5 was utilized to deduce corrected hemoglobin (CHb). The comparison of this CHb with HbD gave a non-significant (P≤0.05) difference. Similarly, linear regression of CHb with PCV gave a 99% prediction. We accordingly recommend a simplified pen-side hematological formula for deducing Hb concentration from PCV viz. Hb concentration= 0.24(PCV) +1.5 for beetal goats instead of its calculation as one-third of PCV.

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Hirsch, Rhoda Elison, Vladimir Malashkevich, Tatiana C. Balazs, and Steven C. Almo. "High Resolution Tertiary and Quaternary Structural Changes in Deoxy and Liganded Hemoglobin E." Blood 112, no. 11 (2008): 540. http://dx.doi.org/10.1182/blood.v112.11.540.540.

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Abstract Hemoglobin (Hb) E (β26 Glu→Lys), known to be more unstable than HbA in vitro, remains an enigma in terms of its contributions to red blood cell (RBC) pathophysiological mechanisms. EE individuals exhibit a mild, chronic anemia while HbE-β thalassemia individuals show a range of clinical manifestations, including high morbidity and death, often resulting from cardiac disease. To determine pathophysiological consequences originating from HbE, we created a transgenic mouse expressing exclusively human HbE with equivalent α- and β-chains [Chen et al., Blood 106(11):892a, 2005]. This mice model exhibited hematological characteristics similar to human EE individuals: microcytic RBC with low MCV, low MCH but normal MCHC; target RBC; mild anemia with low Hb, low HCT, elevated reticulocytes; and decreased osmotic fragility. These RBC parameters correlated with indications of mild RBC oxidative stress. Importantly, the transgenic mouse model allows us to obtain purified HbE for crystal growth and dynamic studies, without the presence of human HbA2 (co-expressed in human HbE RBC and difficult to separate). We now present the low [PDB 1YVQ] and high salt [PDB 1YVT] liganded COHbE structures (1.8Å resolution) at or near physiological pH. The known in vitro instability of oxy HbE and its propensity for oxidation may be explained by the substitution of the β26 side-chain with Lys resulting in a positive charge repulsion with consequential changes to β117, and other key stabilizing residues at the α1β1 interface that impart normal association and oxidative stability to HbA. The specific alterations observed in this microenvironment may be the key to HbE instability, given the findings by Adachi et al. (Biochemistry, 42:10252, 2003) that β116 in normal HbA plays a critical role in stabilizing α1β1 interactions and inhibiting oxidation. Additionally, the difference in water structure observed in each of our COHbE structures from crystals generated under different conditions clearly suggests that resolved water structure is dependent simply upon crystallization conditions, and caution must be taken in interpretation of thermal instability. The 1.6 Å structure of deoxy HbE [PDB 3DUT] (crystallization conditions: pH 6.8, 1.8M ammonium phosphate/ammonium sulfate/citrate) exhibits definitive quaternary change compared to the deoxy HbA structure obtained under similar conditions. These structural findings, explain in part, our recent spectroscopic findings of alterations in oxy and deoxy HbE-nitrite interactions.

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Friedrich, M., and H. M. Rein. "Analytical current-voltage relations for compact SiGe HBT models. II. Application to practical HBTs and parameter extraction." IEEE Transactions on Electron Devices 46, no. 7 (1999): 1394–401. http://dx.doi.org/10.1109/16.772481.

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Farooq, Umer, Musadiq Idris, Nouman Sajjad, et al. "Investigating the potential of packed cell volume for deducing hemoglobin: Cholistani camels in perspective." PLOS ONE 18, no. 5 (2023): e0280659. http://dx.doi.org/10.1371/journal.pone.0280659.

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In human medical practice, a hematological rule of three has been validated for healthy human populations. One such formula is estimating hemoglobin (Hb) levels as 1/3rd of Packed Cell Volume (PCV). However, no such hematological formulae have been devised and validated for veterinary medical practice. The present study was devised with an aim to evaluate the relationship between hemoglobin (Hb) concentration and Packed Cell Volume (PCV) in camels (n = 215) being reared under pastoralism, and to devise a simple pen-side hematological formula for estimation of Hb from PCV. The PCV was determined through microhematocrit method whereas Hb estimation by cyanmethaemoglobin method (HbD). The Hb was also calculated as 1/3rd of PCV and was dubbed as calculated Hb (HbC). Overall HbD and HbC were significantly (P≥0.05) different. Similar results were attained for all study groups i.e. males (n = 94) and females (n = 121), and young (n = 85) and adult (n = 130) camels. The corrected Hb (CHb) was deduced through regression prediction equation attained from linear regression model. Scatterplots were drawn, linear regression was carried out, and Bland Altman chart was built for agreement of both methods of Hb estimation. A non-significant (P≥0.05) difference was noticed between HbD and CHb. Bland Altman agreement analysis revealed satisfactory agreement between HbD and CHb and the data was distributed closely around the mean difference line (Mean = 0.1436, 95% CI = 3.00, -2.72). A simplified pen-side hematological formula for deducing Hb concentration from PCV is accordingly recommended viz. Hb concentration (g/dL) = 0.18(PCV)+5.4 for all age and gender groups of camels instead of its calculation as one-third of PCV.

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BRAVINA, L., L. V. MALININA, I. ARSENE, M. S. NILSSON, L. I. SARYCHEVA, and E. ZABRODIN. "STUDY OF PARTICLE CORRELATIONS AT RHIC ENERGIES WITHIN THE QUARK-GLUON STRING MODEL." International Journal of Modern Physics E 16, no. 07n08 (2007): 2116–22. http://dx.doi.org/10.1142/s0218301307007556.

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The experimental data obtained by the Relativistic Heavy Ion Collider (RHIC) have shown surprisingly large elliptic flow and small correlation (Hanbury-Brown-Twiss, HBT) radii. Quark-Gluon String Model (QGSM) is found to reproduce well many of the flow features in heavy-ion collisions, whereas the models based on the longitudinal excitation of strings essentially underpredict the elliptic flow seen at RHIC. Our aim is to study the HBT correlations within the same QGSM approach. The transverse momentum dependence of correlation radii R long , R out and R side obtained in the QGSM is compared with the UrQMD transport model calculations and the experimental STAR data at [Formula: see text] for the central Au + Au collisions. It appears that the correlation radii obtained in the QGSM from the analysis of all pions are essentially smaller than the experimental ones, while for pions coming from the decay of resonances the agreement with the experimental data is very good.

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Zhang, Wenqian, Mei Ge, Yi Li, Shuxin Tan, Chenhui Yu, and Dunjun Chen. "TCAD Simulation of an E-Mode Heterojunction Bipolar p-FET with Imax > 240 mA/mm." Electronics 13, no. 23 (2024): 4752. https://doi.org/10.3390/electronics13234752.

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This work demonstrates an enhancement mode heterojunction bipolar p-FET (HEB-PFET) structure with a AlGaN/GaN heterojunction bipolar transistor (HBT) integrated on the drain side. Such device design notably contributes to the ultra-high output current density, which is conventionally limited by the low hole mobility and concentration in the p-FETs. The HEB-PFET exhibits an output current density of 241 mA/mm, which is 134 times larger compared to the conventional p-FET (C-PFET) and 2.4 times of the homojunction bipolar p-FET (HOB-PFET). This can be attributed to a better current gain of HBT than homojunction bipolar transistor (BJT). An optimized HEB-PFET of 6 nm p-GaN layer beneath the gate is proposed, where ION/IOFF is >1011, and Vth is −0.44 V. Additionally, thermal stabilities are studied with temperature changes from 300 K to 425 K. Moreover, a semi-empirical compact model is presented to visually explain the working principle of the HEB-PFET.

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Ortiz-Zambrano, Edison Bolivar, Jefferson Torres-Quezada, and José Fabián Véliz-Párraga. "Evaluación térmica y lumínica en prototipos de cubiertas ligeras, para clima cálido húmedo." Revista Hábitat Sustentable 11, no. 2 (2021): 60–71. http://dx.doi.org/10.22320/07190700.2021.11.02.05.

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The zinc sheet roof is one of the most popular elements in Latin American architecture, and in many other regions with warm humid climates. Creating lighting and thermal alternatives focused on this typology would imply major benefits in the environmental and social fields. This study carried out in Manabí, Ecuador, evaluates three prototypes of light roofs, combining zinc with PVC, in order to determine the correct configuration of translucent material to create environments that are within thermal and lighting parameters. The results indicate that the empirical solutions model has the lowest variation in indoor temperature, with 32.63%, unlike the 32.97% of the cross-type model, and the 34.40% of the side strip model. Additionally, it was seen that the greatest influence of solar radiation on the roof is recorded from 1:00 p.m. to 2 p.m. approximately

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