HEMT Model Research Articles

Design and Development of GaN-Based Power Amplifier for Radar Applications

This paper presents a comprehensive overview of Gallium nitride (GaN)-based power amplifier (PA) design for various frequency bands. GaN-based technology has emerged as a promising alternative to traditional silicon-based amplifiers due to its superior performance characteristics, which are discussed in this paper. This paper also discusses the key design parameters and challenges associated with PA design. Various design techniques and topologies for GaN power amplifiers are explored besides addressing theoretical considerations of PA design along with a complete systematic design procedure for L-Band amplifier using the wolfspeed large signal GaN HEMT model. To further demonstrate the useful methodology, the designs of S-band and C-band PAs are also presented. GaN-based devices are very promising candidates for high-power applications. It is widely used in various high-power applications including communication and radar.

A compact Non-Quasi-Static small-signal model for GaN HEMT

In this work, we introduce a compact Non-Quasi-Static (NQS) model for the long-channel Gallium nitride high-mobility field effect transistor based on charge-based EPFL (École Polytechnique fédérale de Lausanne) HEMT model implemented in Verilog-AMS modeling language. The proposed model has been validated for the low-frequency (quasi-static) operating region as well as high frequencies up to sub-terahertz. This model has been derived from the analytical solution of the drift–diffusion and continuity equations based on physically valid assumptions. Polynomial approximation was used to make the model design-oriented and compatible with conventional circuit simulators for designing microwave circuits. Intrinsic trans-admittance parameters, obtained from the model for two devices with channel lengths of 1μm and 10μm has been validated with TCAD simulation results. Besides, the scattering parameters for the GaN HEMT equivalent circuit, have been validated with TCAD simulations and with our previous work, which already validated with experimental data. These results confirm the effectiveness of the proposed compact model for circuit simulations.

Design of Inner Matching Three-Stage High-Power Doherty Power Amplifier Based on GaN HEMT Model.

This paper introduces the structure and characteristics of an internal-matching high-power Doherty power amplifier based on GaN HEMT devices with 0.25 μm process platforms from the Nanjing Electronic Devices Institute. Through parameter extraction and load-pull testing of the model transistor, an EE_HEMT model for the 1.2 mm gate-width GaN HEMT device was established. This model serves as the foundation for designing a high-power three-stage Doherty power amplifier. The amplifier achieved a saturated power gain exceeding 9 dB in continuous wave mode, with a saturated power output of 49.7 dBm. The drain efficiency was greater than 65% at 2.6 GHz. At 9 dB power back-off point, corresponding to an output power of 40.5 dBm, the drain efficiency remained above 55%. The performance of the amplifier remains consistent within the 2.55-2.62 GHz frequency range. The measured power, efficiency, and gain of the designed Doherty power amplifier align closely with the simulation results based on the EE_HEMT model, validating the accuracy of the established model. Furthermore, the in-band matching design reduces the size and weight of the amplifier. The amplifier maintains normal operation even after high and low-temperature testing, demonstrating its reliability. In conjunction with DPD (digital pre-distortion) for the modulated signal test, the amplifier exhibits extremely high linearity (ACLR < -50.93 dBc). This Doherty power amplifier holds potential applications in modern wireless communication scenarios.

Switching Loss Model for Fast-Switching GaN HEMT in Half-Bridge Circuit Considering Parasitic Inductance and Temperature Effect

Switching Loss Model for Fast-Switching GaN HEMT in Half-Bridge Circuit Considering Parasitic Inductance and Temperature Effect

An Improved Nonlinear I‐V Model for GaN HEMTs

An Improved Nonlinear I‐V Model for GaN HEMTs

A Hybrid GaN HEMT Model Merging Artificial Neural Networks and ASM-HEMT for Parameter Precision and Scalability

A Hybrid GaN HEMT Model Merging Artificial Neural Networks and ASM-HEMT for Parameter Precision and Scalability

A Multitime-Scale Analytical Model of ZVS Buck Converter

This paper presents a modeling method to build the complete and accurate multi-time-scale analytical model for low-voltage eGaN HEMTs based zero voltage switching (ZVS) Buck converter with consideration of parasitic inductors, nonlinear junction capacitors and nonlinear transconductance, etc. The switching steady-state modes and switching transient modes are discussed in detail based on their corresponding equivalent circuits. The state equations of each mode are solved by MATLAB software to obtain the key operating waveforms throughout one switching cycle. Moreover, the established switching steady-state model and switching transient model are numerically merged together through continuous state variables, and then the multi-time-scale model for stable operation is formed based on the iterative method. The waveforms and switching energy losses predicted by the model within one switching cycle are compared with the experimental results, respectively, to verify the accuracy of the model. In the end, the dead time is optimized based on the proposed model, and the optimization result is verified to be effective in reducing the switching energy loss through experiment.

A novel large‐signal GaN HEMT modeling based on harmonic mean

AbstractA novel large signal compact modeling for GaN HEMT has been proposed in this paper, and the harmonic mean is used to simulate the I‐V curves, combining the saturation and the linear region. The traditional compact modelings has two typical forms, the empirical modeling and the physical modeling. The empirical modeling is accurate and fast, but lacking the physical meaning. On the contrary, the physical modeling derived from the physical equation, is more complex, with the low speed and the poor convergence. This novel modeling inherently has both advantages, the fast speed, and so forth, and the physical meaning. The saturation region covers the most states of the power amplifiers, and Chih‐Tang Sah equation with clear physical meanings is adopted in this region. In linear region, on the contrary, the current varies more steeply with the voltage, and thus the empirical formula is used.

Threshold voltage shift model for p-GaN gate enhancement mode HEMT

In this paper, we based on the gate structure of p-GaN HEMT connected with Schottky diode and PIN diode and analyzed the threshold voltage shift mechanism under the influence of gate voltage. Based on the carrier transport mechanism, the electron injection current and hole injection current of the p-GaN layer is discussed and calculated, while the gate current model and threshold voltage shift model of the p-GaN HEMT are analyzed. The accuracy of the model is verified by comparing with the experimental data. The effects of p-GaN doping concentration, AlGaN barrier layer thickness and Al component on the gate current and VTH shift are discussed based on the model. By optimizing the device structure and process parameters, the gate current of HEMT can be reduced and the stability of VTH can be improved.

Efficient field-circuit co-simulation method for GaN-based high power microwave devices

Due to the development of the third-generation semiconductors representative of gallium nitride (GaN), the microwave power devices are developing towards higher power, higher efficiency and high integration. However, the electromagnetic field effects are more significant inside the device. As a result, circuit-level based simulation techniques can no longer satisfy the accuracy requirements of device design. Therefore it is necessary to urgently establish the field-circuit co-simulation techniques to couple the active GaN devices with passive electromagnetic structures. In this work, we propose a high-precision discontinuous Galerkin time-domain method to analyze the performances of GAN-based high-power microwave devices. The extracted large-signal compact model of the GaN HEMT is incorporated into the electromagnetic field equations. A local time-stepping technique is adopted to remove the constraints of nonlinear compact models and multiscale elements on the stability conditions of the global algorithm. The comparisons among numerical simulations, experimental results, and software calculations demonstrate the excellent accuracy and efficiency of the proposed method, which can provide a theoretical analysis and design tool for the high reliability design of advanced high-power microwave devices.

Compact small‐signal equivalent circuit statistical analysis model of microwave wide bandgap gallium nitride high electron mobility transistors

In the fabrication process of wide bandgap gallium nitride high electron mobility transistors (GaN HEMT), due to the process error, process fluctuation, material defects, and other factors, wide bandgap semiconductor transistors produced in different batches will also have dispersed fluctuation of electrical characteristics under these special working conditions, which results in deviations between ideal software simulation parameters based on device model and the actual measurement parameters. Some statistical analysis methods like principal component analysis, factor analysis, and multivariate statistical regression in this article are introduced to process S-parameter which can be measured from different batches of CGH40010 GaN HEMT and statistical model parameters can be got from them. Error of S-parameter comparison are less than 10% between calculation results of established small-signal statistical equivalent circuit model (ECM) and S-parameter sample measurement results. Monte Carlo simulation based on statistical model can be well adopted to predict dispersed fluctuation of electrical characteristics for different samples and which can be used as the basis of large-signal ECM statistical model.

A circuit‐based neuro‐space mapping technique for small‐signal modeling of multi‐gate GaN HEMT switches

GaN HEMT switches has become more and more important in RF front-end. This article proposes a circuit-based neuro-SM technique for the small-signal modeling of multi-gate GaN HEMT switches for the first time. A general equivalent circuit model for multi-gate switch HEMT is proposed using the cascaded single-gate switch HEMT model to represent the tendency rather than the exact behaviors of the small-signal responses. We utilize this proposed equivalent circuit model as the coarse model and propose a novel circuit-based neuro-SM modeling technique. Neural networks are incorporated to learn the difference between the coarse model and the fine device data, improving the neuro-SM model accuracy. After being trained, the obtained neuro-SM model can be used for high-level circuit design to increase the speed and accuracy of circuit design. Compared to the existing modeling techniques for multi-gate switches, the proposed neuro-SM achieves better model accuracy. Examples of a dual-gate GaN HEMT switch and a triple-gate GaN HEMT switch have been examined.

High-Temperature HEMT Model

Taking into account the impact of self-heating and temperature rise effects, this work presents a physics-based analytical model for HEMTs, operating continuously from room temperature to high temperatures in linear and saturation regimes. Relying on the core École Polytechnique Fédérale de Lausanne (EPFL) HEMT model, the temperature dependence of various parameters including mobility, saturation velocity, critical electric fields, access region resistance, threshold voltage, and subthreshold slope was taken into account in the model. The accuracy of the developed model is validated by the TCAD simulation results and experimental data over a wide range of ambient temperatures from −20 °C to 500 °C.

A strategy dedicated to the concise and efficient development of the customized large-signal model for GaAs HEMTs

In this letter, a strategy dedicated to the concise and efficient development of the customized large-signal models for GaAs HEMTs is proposed, which is specialized for MMIC designers. The core concepts of the strategy are a deconstruction of the original thought of model construction and dimension reduction of the objective functions of optimization algorithms. The development of an Angelov-based customized large-signal model following this strategy has been successfully applied to GaAs HEMTs in 70nm process. The results show that it takes less than five minutes to execute such a parameter extraction algorithm with a one-button extraction function and good agreement is achieved between the model simulation and device measurement up to 65GHz.

An Improved Compact Large-Signal GaN HEMT Model for Switch Application

The accurate current model near knee voltage is critical to precisely simulate the power compression characteristics for power high-electron-mobility transistor (HEMT), especially for high-power-switch applications. An improved compact large-signal gallium nitride (GaN) HEMT model for high-power-switch applications is proposed in this article. The proposed model employs an additional slope factor in terms of hyperbolic tangent function to improve the model accuracy and flexibility of the knee current in both positive and negative regions. Besides, the improved GaN HEMT model counting in intrinsic capacitance variation of drain–source capacitance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}_{\text{ds}}$ </tex-math></inline-formula> and gate–source capacitance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}_{\text{gs}}$ </tex-math></inline-formula> can characterize the nonlinear voltage-dependent performance of HEMT even when the HEMT is biased below pinchoff voltage. The modeling of intrinsic nonlinear capacitance below the pinchoff voltage achieves improved accuracy of isolation simulation for GaN HEMT switches under large-signal excitation. The proposed model is verified by measurements, including dc <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}{-}{V}$ </tex-math></inline-formula> characteristics, small-signal <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> -parameters, as well as large-signal power compression and harmonic characteristics. The proposed model will be useful for the design of RF switches.

Circuit Models of Power MOSFETs Leading the Way of GaN HEMT Modelling—A Review

Gallium nitride high-electron-mobility transistor (GaN HEMT) is a key enabling technology for obtaining high-efficient and compact power electronic systems. At the design stage of a power converter, the proper modelling of the GaN HEMT is essential to benefit from their good features and to account for the limits of the current technology. Circuit models of power MOSFETs have been deeply investigated by academia and industry for a long time. These models are able to emulate the datasheet information, and they are usually provided by device manufacturers as netlists that can be simulated in any kind of SPICE-like software. This paper firstly highlights the similarities and differences between MOSFETs and GaN HEMTs at the datasheet level. According to this analysis, the features of MOSFET circuit models that can be adopted for GaN HEMT modelling are discussed. This task has been accomplished by overviewing the literature on MOSFETs circuit models as well as analysing manufacturers netlists, thus highlighting the models MOSFETs valid or adaptable to GaN HEMTs. The study has revealed show that some models can be adapted for the GaN HEMT devices to emulate static characteristics at room temperature while the MOSFET models of dynamic characteristics can be used for GaN HEMT devices. This study enables the devices modellers to speed up the GaN HEMT modelling thanks to the use of some well-established MOSFET models. In this perspective, some suggestions to develop accurate GaN HEMT models are also provided.

Modeling the Impact of Dynamic Fin-Width on the I– V, C– V and RF Characteristics of GaN Fin–HEMTs

In this article, we introduce an engineering approach to model the current and charge characteristics of an AlGaN/GaN Fin–HEMT. The model handles the effective width of the 2DEG channel by considering its depletion due to the presence of gates on the sidewalls of the fin. This width modulation of the 2DEG, and the bias-dependence associated with it, significantly affects the transconductance and the capacitance behavior of the device. In this work, we modify and couple two industry-standard compact models: 1) the advanced SPICE model for GaN HEMTs (ASM-GaN-HEMT) model and 2) the Berkeley short-channel insulated-gate FET model for common multiple gate (BSIM-CMG) model. While the former provides the physics-based calculations for electrostatics and transport in the 2DEG, the latter is incorporated to account for the width-modulation due to the sidewalls. The developed methodology is validated for dc, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}$ </tex-math></inline-formula> , and RF behavior against experimental data of GaN Fin–HEMTs. To the authors’ knowledge, this is the first compact model that provides an end-to-end dc–radio frequencies (RF) modeling solution for the state-of-the-art GaN Fin–HEMTs and therefore could play a role in the evolution of the GaN Fin–HEMT technology.

An Accurate Switching Transient Analytical Model for GaN HEMT under the Influence of Nonlinear Parameters

The Gallium Nitride high electron mobility transistor (GaN HEMT) has been considered as a potential power semiconductor device for high switching speed and high power density application since its commercialization. Compared with the traditional Si transistors, GaN HEMT has faster switching speed and lower on-off loss. As a result, it is more sensitive to the nonlinear parameters due to the fast switching speed. The subsequent voltage and current overshooting will affect the efficiency and safety of the GaN HEMT and power electronic systems. In this paper, an accurate switching transient analytical model for GaN HEMT is proposed, which considers the effects of parasitic inductances, nonlinear junction capacitances and nonlinear transconductance. The model characteristic of turn-ON process and turn-OFF process is illustrated in detail, and the equivalent circuits are derived for each switching transition. The accuracy of the proposed model can be verified by comparing the predicted switching waveform and switching loss with that of the experimental results based on the double pulse test (DPT) circuit. Compared with the conventional model, the proposed model is more accurate and matches better with the experimental results than the conventional model. Finally, this model can be used for analyzing the influences of gate resistance, nonlinear junction capacitances, and parasitic inductances on switching transient waveform and refining calculation switching loss.

Behavioral-level modeling of GaN HEMT small-signal intrinsic noise based on DE-SVR algorithm

The Differential Evolution-Support Vector Regression (DE-SVR) algorithm is designed to model the small-signal intrinsic noise behavior of GaN HEMT. It not only overcomes the local minimization shortcoming of the Back Propagation (BP) algorithm, but also uses the DE (Differential Evolution) algorithm to obtain the best parameter c (punishment factor) and parameter g (variance of kernel function) of the Support Vector Regression (SVR) algorithm. In order to validate the superiority of the DE-SVR algorithm, the experiment compares the modeling effects of BP algorithm, SVR algorithm, and DE-SVR algorithm in modeling the small-signal intrinsic noise model of GaN HEMT. The experimental results show that there are obvious advantages for the DE-SVR algorithm in modeling the small-signal intrinsic noise characteristics of GaN HEMT.

Small‐signal modeling of microwave transistors using radial basis function artificial neural network‐comparison of different methods for spread constant determined

This article presents a high-precision modeling method to build a small signal model of GaAs pseudomorphic high electron mobility transistor (pHEMT) by using a radial basis function artificial neural network (RBF ANN). Both the RBF ANN Method 1 that uniformly distributed spread constant (SC) in the given range and Method 2 that increasingly changed SC with a chosen step have been modeled in this work. Compared with the l RBF ANN Method 1, the RBF ANN method 2 can automatically obtain the optimal ANN corresponding to the SC. The RBF ANN method 2 is developed for S-parameters model and equivalent circuit parameters (ECPs) model of HEMTs. S-parameters model establishes S-parameters versus bias, temperature and frequency, while the ECPs model establishes ECPs versus bias and temperature. To validate the capability of the RBF ANN in small signal modeling of GaAs pHEMTs, measured and modeled data of S-parameters model and ECPs model of a 4 × 75 μm gate width, 0.15 μm gate length GaAs pHEMT are compared, and very good agreement is achieved up to 50 GHz. For the S-parameters model, the average error of the method 2 is improved by about 20% at the temperature of −20°C, 25°C, and 85°C. For the ECPs model, the average error of the method 2 is 80% higher than that of the method 1.