Vertical Bipolar Inter-company Research Articles

SPICE2G and PSPICE Circuit Simulation of h and g Two Port Networks

Methods to simulate two port electronics circuits whose hybrid (h) and inverse hybrid (g) parameters are available for circuit designer are given using Spice2G/Pspice analysis programs. Starting from the definitions of two port h parameters, Spice2G and Pspice compatible equations for various frequencies are derived and compatible sub circuits for h,g two ports are obtained both at DC and AC. Effective and extensive use of Spice2G elements (voltage/current controlled current/voltage sources) has been made to obtain models. Both FREQ and VALUE descriptions of analog behavioural modelling of Pspice are used to obtain sub circuits at DC and AC. The h-parameter and g-parameter two port models for a vertical bipolar intercompany SiGe HBTs have been realised using Spice2G and Pspice. The models are realised at both DC and high frequencies (1GHz-5GHz) using Spice compatible statements for describing circuit elements and parameters. Simulation results for a typical small signal HBT (I C =2.14mA, V CE =3volts, I B = 10mA ) in a circuit using h(g) intrinsic model description are given. Keywords: Simulation, analog electronics, circuits, spice, Pspice, two ports Cite this Article K. Bharath Kumar. SPICE2G and PSPICE Circuit Simulation of h and g Two Port Networks. Recent Trends in Electronics & Communication Systems . 2019; 6(3): 16–25p.

SiC BJT Compact DC Model With Continuous- Temperature Scalability From 300 to 773 K

The first vertical bipolar intercompany (VBIC)-based compact dc model has been developed and verified for a low-voltage 4H-SiC bipolar junction transistor to continuously map a wide temperature range from 300 to 773 K. Temperature and doping dependent physical models for bandgap, incomplete ionization, carrier mobility, and lifetime have been taken into account to give physically meaningful fitting parameters for the compact model. Isothermal simulations using the default VBIC model are performed to extract key parameter sets from measured data at seven different temperature points. Then new temperature dependent equations for the key parameters are proposed and embedded in the default VBIC model. Consequently, a single set of model parameters at 300 K is used to achieve fitting over a wide temperature range from 300 to 773 K. This new model can be used for simulating circuits that require continuous description of device dc performance over a wide temperature range.

An Improved VBIC Large-Signal Equivalent-Circuit Model for SiGe HBT With an Inductive Breakdown Network by <formula formulatype="inline"><tex Notation="TeX">$X$</tex> </formula>-Parameters

In this paper, the $X$ -parameter measurements are applied first to establish an improved vertical bipolar inter-company (VBIC) large-signal equivalent-circuit model for silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs), which can accurately describe novel and unusual characteristics of inductive behavior at breakdown that can occur in the active region under large-signal drive. This improved VBIC model presented here for SiGe HBTs is modified by incorporating a nonlinear base–collector junction breakdown network to account for the RF avalanche delay effect in the breakdown region. Good agreement between simulated and measured $X$ -parameters, which contain small-signal $S$ -parameters, large-signal spectrum, and hot $S$ -parameters, is achieved, validating the presented large-signal VBIC model in the breakdown region. The determined breakdown inductance and resistance agree well with the theoretical results. This modified model can be used to describe and predict RF large-signal performance accurately when transistors are operated in the breakdown and active regions.

An enhanced model for InGaP/GaAs heterojunction bipolar transistor

This paper presents an improved InGaP/GaAs heterojunction bipolar transistor (HBT) model based on the Vertical Bipolar Inter-Company (VBIC) model. New transport current expression is proposed by considering the heterojunction effect. Collector capacitance is developed due to the mobile charge modulation, and the transit time formula is improved to account for electron velocity variation with the collector field under high current. The extraction flow is demonstrated. The new model has been verified by measurements on I–V, S-parameter, cut-off frequency and large-signal conditions.

The model parameter extraction and simulation for the effects of gamma irradiation on the DC characteristics of InGaP/GaAs single heterojunction bipolar transistors

In this article, we report the effect of gamma irradiation on the DC characteristics of InGaP/GaAs single heterojunction bipolar transistors (SHBTs) based on the simulation with the extracted model parameters from experiment data before irradiation, after irradiation and after annealing. A simplified Vertical Bipolar Inter-Company (VBIC) static model is proposed to study the operational mechanism and the DC characteristics of SHBTs. The results show that the defects induced by irradiation are responsible for the changes on the DC characteristics of the devices.

Silicon controlled rectifier (SCR) compact modeling based on VBIC and Gummel–Poon models

Silicon controlled rectifier (SCR) is frequently used for electrostatic discharge (ESD) protection applications. For computer-aided design purposes, a macromodel can be constructed for such a device, but a model for the NPN and PNP bipolar transistors imbedded in the SCR is required in the macromodel development. In the paper, we use both the Vertical Bipolar Inter-Company (VBIC) and SPICE Gummel–Poon (SGP) models for these bipolar transistors and compare the perspective macromodel results. Measurements obtained from the transmission line pulsing (TLP) tester are also included to assess the suitability and pros and cons of the VBIC and SGP models for the SCR ESD modeling.

Study of Electrical Stress Effect on SiGe HBT Low-Noise Amplifier Performance by Simulation

This paper investigates the hot-carrier-induced performance degradation in a cascode low-noise amplifier using SiGe heterojunction bipolar transistors. Changes in device characteristics due to accelerated hot-carrier stress are examined experimentally. The vertical bipolar inter-company (VBIC) model parameters extracted from measured device data before and after stress are used in Cadence SpectreRF simulation to evaluate the circuit performance degradation

Improved VBIC model for SiGe HBTs with an unified model of heterojunction barrier effects

An improved bipolar transistor model considering heterojunction barrier effect (HBE) in SiGe double heterojunction bipolar transistors is developed. The effect of barrier formation due to high level injection, which is related to the rapid degradations of the dc current gain (/spl beta/) and cutoff frequency (f/sub T/), is carefully investigated and analyzed. As the collector current becomes high, the conduction band barrier is induced and increased. It causes the saturation of collector current (J/sub C/) due to the blocking of carrier transport, the sharp increase of base transit time (/spl tau//sub B/) due to the additional charge storage, the increase of base current (J/sub B/) due to the increased recombination, and the decrease of intrinsic base resistance (R/sub bi/) due to the increased charge and base pushout. Those phenomena are included into a vertical bipolar intercompany model (VBIC) compact model by employing a unified model of the HBE on J/sub C/, J/sub B/, /spl tau//sub B/, and R/sub bi/. Furthermore, portions of /spl tau//sub B/ and R/sub bi/ from the Kirk effect itself are modeled according to the high current model description and the new formulation of widened base, respectively. A full extraction of parameters has been performed and the modified VBIC model is applied. The modeling accuracy is significantly improved at the high current region for the dc and RF characteristics.

Implementation of a scalable VBIC model for SiGe:C HBTs

This work examines the utility of semi-physical vertical bipolar inter-company (VBIC) model for the first time to develop for an accurate, easy and fast scaling methodology for high-frequency SiGe:C heterojunction bipolar transistors (HBTs) with a peak f T of 75 GHz fabricated in a low-cost BiCMOS technology. The methodology allows one to find transistor models from single-finger transistor to multi-finger and variable length emitter devices with a minimal parameter extraction procedure. The devices modeled include several base–emitter structures in parallel, on top of a single collector to obtain different transistor area. The scaling rules are given in detail. Using this methodology, scalable VBIC model parameters were generated to describe the DC and RF behavior of SiGe:C HBTs up to peak f T and f max within ±10% accuracy. The key advantage of this methodology is that one does not need any special test structure while keeping the extraction procedure simple and fast.

Voltage stress-induced hot carrier effects on SiGe HBT VCO

This paper presents the hot carrier (HC) induced performance degradation in a 10 GHz voltage controlled oscillator (VCO) with SiGe heterojunction bipolar transistors (HBTs). SiGe device characteristics due to HC stress are examined experimentally. The vertical bipolar inter-company (VBIC) model parameters extracted from measured data are used in Cadence SpectreRF simulation to verify the HC effect on the VCO. The VCO shows significant vulnerability to hot carriers.

Enhanced high-current VBIC model

The widely used vertical bipolar inter-company (VBIC) model for bipolar junction transistor-heterojunction bipolar transistors (HBTs) was modified to incorporate high-current effects. The modified VBIC model keeps all features of the original model and adds new features such as mobile carrier modulation of the base-collector capacitance, high-current Kirk effects, high-current reverse emitter-base injection, and current dependence of the reverse transit time in HBTs. The new model accurately fits the dc I-V characteristics, the bias-dependent transit-time, and S-parameters at active and quasi-saturation region biases. It is shown that the new formulation accurately models the strong current dependence of f/sub t/ and G/sub max/ over a wide range of biases. It also predicts very well the power performance in class-AB operation and at the loading for maximum power-added efficiency and maximum output power. The model also shows good fitting of two-tone linearity characteristics when simulated with the same fundamental and harmonic load conditions as in the measurements.

Substrate Leakage Current in InGaP/GaAs Heterojunction Bipolar Transistors

Substrate leakage current in InGaP/GaAs heterojunction bipolar transistors (HBTs) has been observed. For a substrate thickness of 100 µm and an emitter area of 60 µm2, the parasitic current is on the order of 10-8 A. The current flowing between the collector terminal and the substrate can be decomposed into linear and parabolic components. The parabolic dependence is also observed in Medici simulation. A theoretical derivation based on electron drift in the substrate shows parabolic dependence on applied voltage, consistent with our measurement and Medici simulation. In addition, it has been found that the current is inversely proportional to the cube of substrate thickness. To account for this substrate parasitic effect, a modification of the vertical bipolar inter-company (VBIC) model is proposed.

Direct Parameter Extraction of SiGe HBTs for the VBIC Bipolar Compact Model

An improved direct parameter extraction method of SiGe heterojunction bipolar transistors (HBTs) for the vertical bipolar intercompany (VBIC)-type hybrid-/spl pi/ model is developed. All the equivalent circuit elements are extracted analytically from S-parameter data only and without any numerical optimization. The proposed technique of the parameter extraction, differing from the previous ones, focuses on correcting the pad de-embedding error for an accurate and invariant extraction of intrinsic base resistance (R/sub bi/), formulating a new parasitic substrate network, and improving the extraction procedure of transconductance (g/sub m/), dynamic base-emitter resistance (r/sub /spl pi//), and base-emitter capacitance (C/sub /spl pi//) using the accurately extracted R/sub bi/. The extracted parameters are frequency-independent and reliable due to elimination of any de-embedding errors. The agreements between the measured and model-calculated data are excellent in the frequency range of 0.2-10.2 GHz over a wide range of bias points. Therefore, we believe that the proposed extraction method is a simple and reliable routine applicable to the optimization of transistor design, process control, and the improvement of VBIC compact model, especially for SiGe HBTs.

Characterization and Modeling of InGaP HBT Low-Frequency Oscillations

Audio and near-audio frequency oscillations of InGaP heterojunction bipolar transistors (HBT) devices at room temperature have been observed in an environment typical of high-frequency S-parameter device characterization systems. The oscillations are attributed to sufficient phase shift of the low-frequency thermal impedance in combination with a reactive input impedance resulting in system instability. The oscillations are demonstrated through transient circuit simulations using vertical bipolar intercompany models and predicted using a simple small-signal model.

Comparison of state-of-the-art bipolar compact models for SiGe-HBTs

Vertical bipolar inter-company (VBIC) and high current model (HICUM) have been applied for dc modeling of state-of-the-art SiGe-HBTs. The models include improved Early effect, quasi-saturation, substrate parasitic, avalanche multiplication, and self-heating. Several dc parameters of the devices have been extracted from SiGe-HBTs and implemented in the VBIC and HICUM models. A comparison is made also with the SGP model. The usefulness and accuracy of the VBIC and HICUM models for SiGe-HBTs are demonstrated by way of comparison of simulated and measured room temperature device dc data.

Advanced SPICE modelling of SiGe HBTs using VBIC model

The vertical bipolar intercompany (VBIC) model has been applied to silicon-germanium heterojunction bipolar transistors (SiGe HBTs). The model includes the improved Early effect, quasi-saturation, substrate parasitic, avalanche multiplication, and self-heating. Several device parameters have been extracted from SiGe HBTs and implemented in the VBIC model. A comparison is made with the SPICE Gummel-Poon model. The usefulness and accuracy of the VBIC model for SiGe HBTs are demonstrated by way of comparison of simulated and measured room temperature device data.