Gate Charge Model Research Articles

An Accurate Neural Network-Based Consistent Gate Charge Model for GaN HEMTs by Refining Intrinsic Capacitances

Neural network-based capacitance models are accurate, but some of them are not charge-conservative. In this work, a novel consistent gate charge model for GaN high electron mobility transistors is presented based on neural networks. The equivalent circuit parameters are extracted using the multiobjective gray wolf optimizer-based hybrid method, which improves the accuracy of parameter extraction. To obtain more reliable data sets for accurate neural network-based modeling, the outliers in the extracted intrinsic capacitances are automatically detected and removed using the isolation forest technique. The gate charge is obtained by integrating the capacitances with the voltages at different temperatures. A neural network is used to model the bias- and temperature-dependent gate charges, and the intrinsic capacitance formulation is obtained by taking the partial derivative of the gate charge function with respect to the voltages. The proposed model is charge-conservative and requires no transcapacitances. The large-signal model is implemented in the Advanced Design System and verified by small- and large-signal measurements. Good agreement is obtained between the measurements and simulations.

Modeling and simulation of DC and microwave characteristics of AlInN(AlGaN)/AlN/GaN MOSHEMTs with different gate lengths

AbstractIn this paper, direct current (DC) and microwave characteristics are modeled and analyzed for AlInN(AlGaN)/AlN/GaN metal‐oxide‐semiconductor high electron mobility transistors with different gate lengths. The 2‐dimensional electron gas sheet charge density (ns) model is developed by considering polarization effect and flat‐band voltage with lowest occupied energy level (E0) in the quantum well. The drain current, transconductance, and gate charge model is developed by incorporating approximation of ns as proposed in this paper. Then, the cut‐off frequency is calculated from the transconductance and gate capacitance model. The analytical model results are in good agreement with Technology Computer Aided Design simulation and experimental results from literatures for DC and microwave characteristics for the proposed gate lengths (0.1, 0.2, and 0.3 μm). From these characteristics, it is also observed that AlInN/AlN/GaN MOSHEMT shows superior DC and radio frequency performance as compared with AlGaN/AlN/GaN MOSHEMT. AlInN/AlN/GaN MOSHEMT produces high drain current (2.34 A/mm) and high cut‐off frequency (124 GHz) at smaller gate length.

An improved large signal model of InP HEMTs * * Project supported by the National Natural Science Foundation of China (No. 61331006).

An improved large signal model for InP HEMTs is proposed in this paper. The channel current and charge model equations are constructed based on the Angelov model equations. Both the equations for channel current and gate charge models were all continuous and high order drivable, and the proposed gate charge model satisfied the charge conservation. For the strong leakage induced barrier reduction effect of InP HEMTs, the Angelov current model equations are improved. The channel current model could fit DC performance of devices. A 2 × 25 μm × 70 nm InP HEMT device is used to demonstrate the extraction and validation of the model, in which the model has predicted the DC I–V, C–V and bias related S parameters accurately.

A Large-Signal Statistical Model and Yield Estimation of GaN HEMTs Based on Response Surface Methodology

A novel nonlinear large-signal equivalent circuit statistical model of GaN HEMTs based on response surface methodology (RSM) is proposed in this letter. Thirty-four GaN HEMTs from 10 batches are measured and all the parameters in the large-signal equivalent circuit model are extracted by an in-house parameters extraction program. We choose the four most sensitive parameters of the drain-source current model and the gate charge model. The statistical method is modeled by using response surface methodology to change the range of the four parameters. The statistical model is implemented in Agilent-ADS and three S-band GaN HEMT power amplifier are designed by using the established statistical model for validation. The results show that good accuracy has been achieved by comparing measured and simulated output power (Pout) and power added efficiency (PAE). This method is simple and accurate for GaN HEMT power amplifier design and yield estimation.

A novel nonlinear large‐signal statistical model of GaN HEMT used in S‐band power amplifier design and yield estimation

SummaryA novel GaN high‐electron mobility transistor (HEMT) nonlinear large‐signal statistical model based on empirical equivalent circuit is proposed in this paper. Thirty‐four GaN HEMTs from 10 batches are measured, and all the parameters of the large‐signal model are extracted by in‐house parameter extraction program. We choose six most sensitive parameters of the drain‐source current model and the gate charge model. The statistical method is modeled by using a symbolic processing method to change the range of the six parameters. The statistical model is implemented in Agilent ADS software for validation. A S‐band GaN HEMT power amplifier is designed by using the established statistical model for demonstration purpose. The results show that good accuracy has been achieved by comparing measured and simulated output power (Pout) and power added efficiency (PAE). So it has been proven that this method is suitable for GaN HEMT power amplifier design and yield estimation. Copyright © 2016 John Wiley & Sons, Ltd.

Improved large-signal GaN HEMT model suitable for intermodulation distortion analysis

In this article, a complete empirical large-signal model of GaN high electron-mobility transistors (HEMTs) is presented. The developed nonlinear model employs differentiable trigonometric function continuously to describe the drain-source current characteristic and its higher order derivatives, making itself suitable for the simulation of intermodulation distortion (IMD) in microwave circuits. Besides, an improved charge-conservative gate charge model is proposed to accurately trace the nonlinear gate-source and gate-drain capacitances. The model validity is demonstrated for different 0.25-µm gate-length GaN HEMTs. The simulation results of small-signal S-parameters, radio frequency (RF) large-signal power performances and two-tone IMD products show an excellent agreement with the measured data.

A Consistent Charge Model of GaAs MESFETs for $Ku$-Band Power Amplifiers

In this paper, a consistent gate charge model for GaAs MESFETs based upon charge conservation is proposed for monolithic microwave integrated circuit power amplifier designs. This new model is capable of accurately modeling the transistor under various biasing conditions. The conventional approaches for charge modeling of GaAs MESFETs usually adopt analytical equations to fit nonlinear gate capacitors separately, which might be difficult to implement in circuit simulators whose capacitance is always the derivative of an internal state variable (charge). Moreover, compared with the conventional diode and Statz model, the performance prediction in the linear region, saturation knee region, and subthreshold region is greatly improved. Measured and modeled results of a 2 ×150 μm GaAs MESFET are compared and good agreement has been obtained. Comparisons between the proposed model, diode junction model, and Statz model are also presented in this paper. In addition, a class-AB Ku-band power amplifier using a 0.18-μm GaAs MESFET process was designed with the new model for verification of the new model accuracy.

Electrothermal Large-Signal Model of III–V FETs Including Frequency Dispersion and Charge Conservation

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> An empirical large-signal III–V field-effect transistor (FET) model has been developed. Three improved drain-source current (<emphasis emphasistype="bold"><emphasis emphasistype="italic">I</emphasis></emphasis>–<emphasis emphasistype="bold"><emphasis emphasistype="italic">V</emphasis></emphasis>) modeling equations capable of representing arbitrarily shaped transconductance (<formula formulatype="inline"> <tex Notation="TeX">$G_m$</tex></formula>) curves are proposed from level-1 to level-3. These models are characterized by the static dc and the multibias pulsed <emphasis emphasistype="bold"><emphasis emphasistype="italic">I</emphasis></emphasis>–<emphasis emphasistype="bold"><emphasis emphasistype="italic">V</emphasis></emphasis> measurements along with their dependences on temperature, so as to account for the frequency dispersion and the self-heating effects. By partitioning the <formula formulatype="inline"> <tex Notation="TeX">$G_m$</tex></formula> plots into five regions, specific parameters of the various model levels can be directly associated with the regions. Besides, the fitting parameters have inherent consistent definitions among different model levels, where some of the key model parameters can be extracted directly from measurements. For the gate-charge formulation (<emphasis emphasistype="bold"><emphasis emphasistype="italic">Q</emphasis></emphasis>–<emphasis emphasistype="bold"><emphasis emphasistype="italic">V</emphasis></emphasis>), a novel charge-conservative gate charge model is presented to accurately trace the nonlinear gate–source (<formula formulatype="inline"><tex Notation="TeX">$C_{\rm gs}$</tex></formula>) and gate–drain (<formula formulatype="inline"> <tex Notation="TeX">$C_{\rm gd}$</tex></formula>) capacitance values. The comprehensive large-signal model is then validated by comparing the predicted <emphasis emphasistype="bold"><emphasis emphasistype="italic">I</emphasis></emphasis>–<emphasis emphasistype="bold"><emphasis emphasistype="italic">V</emphasis></emphasis>, <emphasis emphasistype="bold"><emphasis emphasistype="italic">C</emphasis></emphasis>–<emphasis emphasistype="bold"><emphasis emphasistype="italic">V</emphasis></emphasis>, <formula formulatype="inline"><tex Notation="TeX">$S$</tex></formula>-parameters as well as power characteristics with the measured results of III–V FETs. </para>

A new rule for MESFET gate charge division based on the energy conservation principle

AbstractThe energy conservation problem in the MESFET gate charge model is presented. The energy conservation requirement leads to symmetrical transcapacitances in contradiction to the commonly accepted approaches. The transcapacitance symmetry is completely independent of device symmetry. The resulting small‐signal capacitances are reciprocal. Reciprocal capacitances are often considered charge non‐conservative because they do not contain transcapacitances, but in this approach reciprocity is the result of transcapacitance symmetry and the charge conservation problem is avoided since the charge‐based model includes the transcapacitances. A method for dividing the MESFET gate charge into gate‐drain and gate‐source portions based on the energy conservation rule is developed, and the method is applied to the well‐known Statz gate charge as an example. Copyright © 2004 John Wiley &amp; Sons, Ltd.