The circuit designer today has programs available which allow him to do a wide variety of analyses. However, the different programs with their differing input formats, rules, notations and device models can be very confusing and discouraging to the inexperienced user. Fortunately, the program input formats and rules are normally well documented, so if mistakes are made they are relatively easily detected (either by the computer, the program or the user). The biggest problem, however, lies in the lack of standardization of the notation and device models being used and the measurement of the model parameters.This book is aimed at reducing the modeling confusion by systematically describing how to model the bipolar junction transistor (BJT). Emphasis is on the nonlinear, large-signal models used in nonlinear dc and transient analyses, since this is where most modeling problems are encountered. The linear model (the well-known hybrid-r model) which is already fairly well documented and easy to work with, is simply a linearized version of the nonlinear model presented. This linearization process is also described. Modeling the Bipolar Transistor Acknowedgments Contents 1. lntroduction Usefulness of Computer-aided Design Objective Structure Notation and Orientation Input and Model Parameters Dependence of Models on the Physics of the Device Model Notation Which Model to Use? 2. Theoretical Derivation of the Models 2.1 lntroduction 2.2 The EM1 Model 2.2.1 The lnjection Version 2.2.2 The Transport Version 2.2.3 An Alternative Form - the Nonlinear Hybrid-pi 2.2.4 Temperature Variation 2.2.5 Summary And Additional Comments 2.3 The EM 2 Model 2.3.1 lmproved dc Characterization 2.3.2 Charge-Storage Effects a) Junction capacitors b) Diffusion capacitors c) Substrate capacitor 2.3.3 Small-Signal (Linearized) EM2 Model 2.3.4 Summary 2.4 The EM3 Model 2.4.1 An lmproved dc Model at a Given Temperature a) Basewidth modulation b) Bdc variation with current 2.4.2 An lmproved Charge-Storage Model at a Given Temperature 2.4.3 An lmproved Variation with Operating Temperature a) Physics-based temperature variation b) Temperature-dependent parameters that require extra input parameters 2.4.4 Small-Signal (Linearized) EM3 Model 2.4.5 Summary and Conclusions 2.5 The GP Model 2.5.1 lntroduction 2.5.2 The Physical Definition of Is 2.5.3 The Components of Ob 2.5.4 Evaluation of qb 2.5.5 Base-Widcning Effects 2.5.6 Comparison of the GP Model with the EM3 Model 2.5.7 Small-Signal (Linearized) GP Model 2.5.8. Summary 2.6 Limitations of the Models a) Three-Dimensional Effects b) Breakdown e) Saturation 3. Parameter Measurements 3.1 lntroduction 3.2 EM1 Model Parameter Measurements 3.3 EM2 Model Parameter Measurements 3.4 EM3 Model Parameter Measurements 3.5 GP Model Parameter Measurement APPENDIX 1 - A COMPARISON OF THE TRANSPORT NOTATION WITH THE INJECTION NOTATION APPENDIX 2 - EM3 MODEL BASEWIDTH MODULATION ANALYS APPENDIX 3 - DERIVATION OF THE FIVE COMPONENTS Qb IN THE GP MODEL APPENDIX 4 - THE ACCURACY OF THE EM3 AND GP BASEWIDTH MODULATION MODELS APPENDIX 5 - THE SMALL-SIGNAL, LINEARIZED EM3 AND GP MODELS APPENDIX 6 - INPUT PARAMETERS CROSS-REFERENCE FOR SLIC, SINC AND SPICE REFERENCES
