Heterojunction Bipolar Transistor Model Research Articles

Small-signal behavioral-level modeling of InP HBT based on SO-BP neural network

In this paper, Snake Optimizer-Back Propagation (SO-BP) neural network algorithm has been proposed to model the small-signal characteristic of InP heterojunction bipolar transistors (HBTs). The SO algorithm can effectively improve the problem of local optima encountered by the BP neural network algorithm. The InP HBT small-signal models have been constructed by using Back Propagation (BP) algorithm, the Genetic Algorithm-Back Propagation (GA-BP) algorithm and the Snake Optimizer-Back Propagation (SO-BP) algorithm. The experimental results verify that the proposed SO-BP neural network algorithm model has the lowest error rate between simulated and measured data. Hence, the SO-BP algorithm is a more effective approach for modeling the small-signal characteristic of InP HBT. The accurate small-signal behavioral-level model of HBT has significant reference value for the application of microwave and millimeter-wave integrated circuits (MMICs).

A novel radiation-dependence model of InP HBTs including gamma radiation effects

In order to predict the lifetime of InP Heterojunction Bipolar Transistor (HBT) devices and related circuits in the space radiation environment, a novel model including gamma radiation effects is proposed in this paper. Based on the analysis of radiation-induced device degradation effects including both DC and AC characteristics, a set of empirical expressions describing the device degradation trend are presented and incorporated into the Keysight model. To validate the effective of the proposed model, a series of radiation experiments are performed. The correctness of the novel model is validated by comparing experimental and simulated results before and after radiation.

Small-signal Modeling of InP HBT based on PSO-ELM Neural Network

Extreme Learning Machine (ELM) is a new learning algorithm for single-hidden layer feedforward neural network, which has been widely used in lots of fields. However, it still has the insufficiency of randomly determining the hidden layer threshold and output weight, which leads to ill-conditioned output. In order to avoid the risk of decreasing prediction accuracy caused by this possibility, the ELM is optimized using particle swarm algorithm. A Particle Swarm Optimization (PSO) enhanced ELM algorithm is proposed to accurately model the small-signal properties of InP Heterojunction Bipolar Transistors (HBTs). PSOELM algorithm solves the problem of unstable prediction data caused by random determination of input weights in ELM. Comparing the modeling effects of the PSO-ELM model and the ELM model under different bias conditions for a 1 μm×15 μm InP HBT, it is proved that the PSO-ELM algorithm has better consistency with the measured data.

Modeling of heterojunction bipolar transistors based on novel Wiener‐type dynamic neural network

A novel Wiener-type dynamic neural network modeling method for heterojunction bipolar transistors (HBTs) is proposed in this article. The model structure of the novel Wiener-type dynamic neural network applicable to HBT modeling is determined by the vector fitting. For the novel Wiener-type dynamic neural network structure, we also proposed a training algorithm applicable to this novel structure to improve its accuracy. We considered the transmission characteristics of the HBT and use the H-parameter to replace the Y-parameter for small-signal analysis. The DC and small-signal model formulas for HBT are also derived. The proposed novel Wiener-type dynamic neural network modeling method does not require detailed parameter information and the internal design structure of the HBT and can model any type of HBT as long as accurate training data are available. In this paper, an application example on modeling a 3 × 30 μ m 2 InGaP/GaAs HBT is presented, and a combined DC and small-signal model is established to demonstrate the accuracy and feasibility of the proposed novel Wiener-type dynamic neural network modeling method. The modeling method can also be used for computer-aided design, and the established models can be more easily applied to circuit simulation.

An Improved Nonlinear Model for Millimeter-Wave InP HBT Including DC/AC Dispersion Effects

An improved millimeter-wave nonlinear model for InP heterojunction bipolar transistor (HBT) is proposed in this letter. The frequency dispersion effect has been taken into account in the Agilent HBT model in Agilent ADS software. Model verification is carried out by comparison of measured and simulated dc and S-parameters up to 110 GHz.

Guest Editorial for the special issue on devices and circuits for millimeter‐wave and THz applications

Guest Editorial for the special issue on devices and circuits for millimeter‐wave and THz applications

High-Frequency Noise Characterization and Modeling of SiGe HBTs

For heterojunction bipolar transistors (HBTs), the noise correlation influences the noise parameters and is therefore relevant for transistor modeling, especially at sufficiently high frequencies. In order to predict the noise correlation, it is necessary to determine the noise transit time in the noise transport model. In this paper, the noise correlation and noise transit time are predicted from the high current model without measured noise data. The four noise parameters are calculated based on the predicted noise transit time and the Y-parameter noise calculation methodology. The extracted noise transit time is validated by the measured result over bias and temperature, which is determined by fitting NFmin of the silicon-germanium (SiGe) HBT between Y-parameter noise calculation methodology and tuner-based noise measurement. It was found that the noise transit time is independent of frequency but dependent on bias and temperature. Also, the results indicate that the calculated four noise parameters based on the extracted noise transit time have a good agreement with the tuner-based noise measurement.

An Improved Noise Model for SiGe HBT With an Inductive Breakdown Network in the Avalanche Region

In this paper, an improved radio-frequency (RF) noise model is extended for silicon germanium (SiGe) heterojunction bipolar transistors (HBTs) by applying RF avalanche delay mechanism to investigate noise performance in the breakdown region where reliability is a concern. The impact of inductive feedback due to base–collector (BC) junction avalanche breakdown on noise performance is analyzed and explained by utilizing this improved noise model incorporating an inductive network. The avalanche effects on noise sources are verified and explained physically by the dead-space theory. The contributions of electrons and holes to the avalanche noise are taken into account by including an electron- and hole-breakdown network in the presented noise model. The presented method is compared with the conventional approach. When the avalanche noise is absorbed by base and collector noise sources as in the conventional RF noise model without a breakdown network, simulated noise parameters deviate from experimental data at breakdown. Instead, good agreement between measured and simulated noise parameters and $S$ -parameters from the presented RF noise model is achieved in the inductive breakdown and active regions. The presented noise model and the obtained parameters can be applied to SiGe HBT circuits for reliability investigation.

Large Signal Model of Heterojunction Bipolar Transistor InP/InGaAs as an Optoelectronic Mixer

A large-signal model of InP/InGaAs single Heterojunction Bipolar Transistor (HBT) has been developed considering spectral performance and mixing. This model is based on Gummel Poon BJT model. HBT InP/InGaAs has been modeled and analyzed in this paper as an optoelectronic mixer (OEM). The HBT proposed was simulated by considering the wavelength of 1310 nm for an up-conversion frequency of 30 GHz. Its characteristics was further investigated to develop the appropriate structure device for OEM application. This proposed HBT InP/InGaAs can be potentially implemented in the broadband Radio over Fiber (RoF) system to perform photodetection and frequency up-conversion.

An empirical DC to high-frequency model for InP/InGaAs HBTs

An empirical DC to high-frequency equivalent circuit model for heterojunction bipolar transistors (HBTs) is presented in this article. This model takes into account the DC soft-knee effect and bias-dependent extrinsic and intrinsic base-collector capacitances and is built over small-signal model based on the S parameters at multiple bias points on wafer measurement. This modeling methodology is successfully applied to predict DC and small-signal S parameters for an InP/InGaAs HBT. Good agreement is obtained between the simulated and measured results.

Small- and large-signal modeling of InP HBTs in transferred-substrate technology

In this paper, the small- and large-signal modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. The small-signal equivalent circuit parameters for TS-HBTs in two-terminal and three-terminal configurations are determined by employing a direct parameter extraction methodology dedicated to III–V based HBTs. It is shown that the modeling of measured S-parameters can be improved in the millimeter-wave frequency range by augmenting the small-signal model with a description of AC current crowding. The extracted elements of the small-signal model structure are employed as a starting point for the extraction of a large-signal model. The developed large-signal model for the TS-HBTs accurately predicts the DC over temperature and small-signal performance over bias as well as the large-signal performance at millimeter-wave frequencies.

Optimization of Abrupt Profile of Germanium in Si/SiGe Heterojunction Bipolar Transistor Specified for Radio Frequency Range Systems

In this paper, we present modeling of Heterojunction Bipolar Transistors (HBT) based on Si / SiGeC very high performance for telecommunications applications dedicated to radio frequency RF. The major objective of our work will be devoted to the influence of the germanium profile on the static and dynamic characteristics of the latter. The optimization of the profile of germanium in the base is a major element in the study of electrical characteristics of the HBT. This optimisation improves the static gain (β) of the transistor, while increasing the germanium profile in the base of 10% to 30%. However, the transition frequency (fT), and the maximum oscillation frequency (fmax) decrease when the profile of germanium is greater than 20%. A numerical modelling approach is investigated using our 2D simulator SIBIDIF, which is based on the Drift-Diffusion Model (DDM). This method solves the continuity equations for electrons and holes and is coupled with the Poissons equation based on the concept of the finite difference mesh.

Measurement and Modeling of Thermal Behavior in InGaP/GaAs HBTs

Thermal-impedance models of single-finger and multifinger InGaP/GaAs heterojunction bipolar transistors (HBTs) are extracted from low-frequency S-parameters that are measured on wafer and at room-temperature, and from temperature-controlled dc measurements. Low-frequency S-parameters at room temperature are accurate for extracting thermal corner frequencies. However, the dc value of the thermal impedance depends on the emitter resistance and the dc current definitions of the HBT model; hence, they need to be extracted together from temperature-dependent dc measurements. The resulting thermal-impedance model explains the low-frequency dispersion well at varying bias conditions, and it is suitable for nonlinear circuit analysis.

Novel microwave power sige heterojunction bipolar transistor with high thermal stability over a wide temperature range

Thermal instability of power SiGe heterojunction bipolar transistor (HBT) at high current over a wide temperature range restricts the applications of the device in RF and microwave circuits. In order to improve the thermal instability, the influences of Ge profile in a base region on the electrical and thermal characteristics of microwave power SiGe HBT are studied with the aid of the model of multi-finger power SiGe HBT established by SILVACO TCAD. It is shown that for the HBT with graded step Ge profile, a higher cut-off frequency fT can be achieved due to the accelerating electric field caused by the graded step Ge concentration in the base region when compared with the device with uniform Ge profile. The influences of temperature on current gain β and fT are weakened, which avoids the drift of electrical characteristics over a wide temperature range. Although the temperature of device is lowered, the temperature of each emitter finger is still non-uniform. Considering the difference in heat dissipation among emitter fingers, a new device with non-uniform emitter finger spacing in layout and a graded step Ge profile in base region is designed. For the new device, the uniformity of temperature among emitter fingers is achieved, higher fT is kept, β and fT are less sensitive to temperature variation. Hence the thermal instability is obviously improved compared with the device with uniform emitter finger spacing and uniform Ge profile in base region, indicating the superiority of the new device at high current over a wide temperature range.

Compact RF non-linear electro thermal model of SiGe HBT for the design of broadband ADC's

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).

Scalable large-signal model for SiGe HBTs

In this article, a scalable large-signal model for SiGe heterojunction bipolar transistors (HBTs) is presented. Compared with SPICE Gummel-Poon model, the proposed model has taken into account the self-heating effects, which is important for large-signal operations. The model includes a new base-collector breakdown description, which has taken the current dependence into account. This model allows exact modeling of all transistor parameters from single emitter size cells to other size devices. The scaling rules are shown in detail. The model is verified by the SiGe HBTs with emitter area of 0.3 × 20.3, 0.3 × 13.9, 0.3 × 9.9, and 0.3 × 1.9 um2. Excellent agreement has been achieved between modeled and measured data over a wide range of bias conditions and signal frequencies. The model has been implemented in Verilog-A using the ADS circuit simulator. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012. © 2012 Wiley Periodicals, Inc.

Direct Extraction Method of HBT Equivalent-Circuit Elements Relying Exclusively on $S$-Parameters Measured at Normal Bias Conditions

A new direct parameter-extraction scheme applied to a heterojunction bipolar transistor (HBT) small-signal equivalent circuit with distributed base-collector junction capacitance is presented. The proposed method relies exclusively on <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -parameters measured at low and high frequencies in normal bias conditions, and without using approximations based on anticipated values. The extraction results obtained from low-frequency modeling allow the extraction of the parasitic inductances at high frequency. This is performed by formulating expressions based on ac-current-source consideration different from the previously published one, without affecting the physical signification of the HBT model. This method presents a simple way for the extraction of the model parameters directly. An experimental validation on an InP double HBT device was carried out, using the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -parameters measured in a frequency range of 40 MHz-50 GHz over a wide range of bias points. The modeling results are presented, showing that the proposed method can yield a good fit between measured and calculated <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -parameters.

Improved base-collector depletion charge and capacitance model for SiGe HBT on thin-film SOI

The SiGe heterojunction bipolar transistor (HBT) on thin film SOI is successfully integrated with SOI CMOS by folded collector. This paper deals with the collector depletion charge and the capacitance of this structure. An optimized model is presented based on our previous research. The results show that the charge model is smoother, and that the capacitance model with considering different current flow areas, is vertical and horizontal depletion capacitances in series, showing that the depletion capacitance is smaller than that of a bulk HBT. The charge and capacitance vary with the increase of reverse collector-base bias. This collector depletion charge and capacitance model provides valuable reference to the SOI SiGe HBT electrical parameters design and simulation such as Early voltage and transit frequency in the latest 0.13 m SOI BiCMOS technology.

Safe Operating Area of GaAs HBTs Based on Sub-Nanosecond Pulse Characteristics

Using a novel sub-nanosecond pulse current-voltage measurement technique, InGaP/GaAs heterojunction bipolar transistors (HBTs) were shown to survive strong impact ionization and to have a much larger safe operating area (SOA) than previously measured or predicted. As the result, an empirical model for impact ionization with both voltage and current dependence was extracted and added to a commercially available HBT model. The modified model could predict the HBT characteristics across the enlarged SOA, as well as the performance of ultra-wideband pulse generators and the ruggedness of continuous wave Class-C power amplifiers.

A Physics-Based Charge-Control Model for InP DHBT Including Current-Blocking Effect

We develop a physics-based charge-control InP double heterojunction bipolar transistor model including three important effects: current blocking, mobile-charge modulation of the base-collector capacitance and velocity-field modulation in the transit time. The bias-dependent base-collector depletion charge is obtained analytically, which takes into account the mobile-charge modulation. Then, a measurement based voltage-dependent transit time formulation is implemented. As a result, over a wide range of biases, the developed model shows good agreement between the modeled and measured S-parameters and cutoff frequency. Also, the model considering current blocking effect demonstrates more accurate prediction of the output characteristics than conventional vertical bipolar inter company results.