GaAs MESFET Model Research Articles

STUDY ON THE INFLUENCE OF ELECTROPHYSICAL CHARACTERISTICS ON THE PARAMETERS OF COMPACT MODELS OF THE COMPONENTS USED IN RADIO FREQUENCY MONOLITHIC INTEGRATED CIRCUITS

In this paper we demonstrate the results of the study on how the geometric parameters effect the model parameters of passive and active components. As we found out, the substrate thickness has the greatest influence on the equivalent circuit model parameters of passive components. Paper demonstrates the influence of the gate length and the gate recess depth on the parameters of small-signal model of the MESFET. The obtained dependences are presented for the MIM capacitor model, inductor model and GaAs MESFET model.

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.

Neuro-space mapping technique for semiconductor device modeling

This paper presents an application of the space mapping concept in the modeling of semiconductor devices. A recently proposed device modeling technique, called neuro-space mapping (Neuro-SM), is described to meet the constant need of new device models due to rapid progress in the semiconductor technology. Neuro-SM is a systematic method allowing us to exceed the present capabilities of the existing device models. It uses a neural network to map the voltage and current signals between an existing device model (coarse model) and the actual device behavior (fine model), such that the mapped model becomes an accurate representation of the new device. An efficient training method based on analytical sensitivity analysis for such mapping neural network is also addressed. The trained Neuro-SM model can retain the speed of the existing device model while improving the model accuracy. The benefit of the Neuro-SM method is demonstrated by examples of SiGe HBT and GaAs MESFET modeling and use of the models in harmonic balance simulation.

A photo-dependent capacitance model of GaAs MESFET's

A new and simple analytical model for determining the photo-effects on the gate–source and gate–drain capacitances of GaAs MESFET's has been presented for both the linear and saturation regions. A new model for the photovoltage developed across the Schottky junction due to the illumination has been used to investigate the photo-dependent characteristics of the above capacitances. It has been observed that the gate–source and gate–drain capacitances are increased with the increase in the incident illumination level to the device in its linear region of operation whereas in the saturation region, the gate–source capacitance is increased but the gate–drain capacitance is observed to be decreased with the increase in the incident optical intensity level. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A seven-parameter nonlinear I– V characteristics model for sub-μm range GaAs MESFETs

A seven-parameter nonlinear current–voltage ( I– V) characteristics model for sub-micrometre range GaAs MESFETs has been developed. In this regard, Ahmed et al. model [IEEE Trans. Electron Devices 44 (1997) 360] for sub-micron GaAs MESFETs has been modified. In this modification, the effects of both drain-to-source voltage, V DS, and gate-to-source voltage, V GS, on the output conductance, g d, have been incorporated. The developed model has been compared with Ahmed et al. model. For this comparison, an improved mean square error (MSE) technique has been employed instead of root mean square (RMS) error technique. An algorithm has also been developed for the optimization of empirical constants of the model. Sub-μm range MESFETs of different aspect ratios have been modeled with greater accuracy by the modified model. The modified model should be a useful tool for the designing of future integrated circuits with sub-micron gate length GaAs MESFETs.

Large‐signal model predicts dynamic behavior of GaAs MESFET model under optical illumination

AbstractThis paper is the result of our research on the large‐signal dynamic behavior (pulsed I/V curves) of a GaAs device, in the overall I/V plane, when the incident optical input power is changed. A complete bias‐ and optical‐power‐dependent large‐signal model for a MESFET is determined from experimental S‐parameters, dc, and pulsed measurements. All derivatives of the model shown here are continuous for a realistic description of circuit distortion and intermodulation. The dependencies of circuit elements with optical illumination and the quiescent operating point are evaluated, and a comparison between theoretical and measured results over optical power and bias ranges is shown. Experimental results show a very good agreement with the theoretical analysis. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 25–31, 2001.

Compact DC model for submicron GaAs MESFETs including gate-source modulation effects

Recent submicron DC GaAs MESFET models (Ahmed et al., IEEE Trans. Electron. Devices, ED-44 (1997) 360) are improved in order to more accurately facilitate non-linear small-signal circuit designs. The Ahmed–Ahmed–Ladbrooke (AAL) model (Ahmed et al., IEEE Trans. Electron. Devices, ED-44 (1997) 360), allowed for the prediction of the DC characteristics of large-signal submicron devices by using the concept of a shift in threshold voltage. The new model proposed in this paper uses a small number of variables and, while improving on the AAL model, retains the essential form of the more common Curtice and Advanced Curtice models (Curtice, IEEE Trans. Microwave Theory Tech., MTT-28 (1980) 4456; de Graaff and klaassen, Compact Transistor Modelling for Circuit Design, Springer, Vienna, 1990) together with accounting for gate-source voltage modulation effects.

Effect of substrate illumination on the characteristics of an ion implanted GaAs OPFET

An analytical model of an ion-implanted GaAs MESFET has been developed considering the illumination from the substrate. The ion-implanted profile of the channel region is represented by Pearson IV distribution. Modulation of the channel opening due to the internal photovoltage has been considered. The I-V characteristics, the photocurrent, the internal photovoltage and the transconductance of the device have been calculated and discussed. The substrate doping concentration is found to affect the overall drain-source current under illumination, which indicates a significant substrate affect on the device characteristics. The illumination also enhances the dram current of the MESFET compared to that in the dark. The I-V characteristics, transfer characteristics and the ratio of drain currents under illumination and in the dark have been plotted and discussed.

Low-noise FET's vulnerability prediction under RF pulsed overloads based on nonlinear electrothermal modeling

In this work we have determined a nonlinear electrothermal model for a low-noise GaAs MESFET, which enables evaluation of the time dependance of the internal temperature rise consecutive to a microwave overload impinging on the gate. This model takes into account the balance between the microwave energy loss under the gate in the active layer and energy conduction through the substrate during the pulse duration. We have conducted experimental determination of the critical peak power level for failure for several pulse durations and with the application of the model, we find that burnout is reached when the internal temperature exceeds 500/spl deg/C. We are able to predict the vulnerability of a low-noise amplifier under microwave overload.

Study of a GaAs MESFET model with ultra-low power consumption

A model of enhancement-mode GaAs MESFET (EFET) for low power consumption and low noise applications has been obtained by using a small-signal equivalent circuit whose component values are derived from the physical parameters and the bias condition. The dependence of the RF performance and DC power consumption on physical, material and technological parameters of EFET is also studied. The optimum range of the physical parameters is given which is useful for the design of active device of ultra low power consumption MMIC.

An accurate large-signal model of GaAs MESFET which accounts for charge conservation, dispersion, and self-heating

A comprehensive large-signal model of a GaAs MESFET is presented to account for charge conservation and effects of dispersion and self-heating. An improved set of capacitance and charge equations, along with an enhanced Triquint Own model (TOM)-like drain current model, is used for consistent small- and large-signal simulations. Charge conservation is satisfied by deriving the capacitance part of the model from charge equations. Transconductance and output conductance dispersion is modeled by combination of a feedback network and a subcircuit, which describes the self-heating effect. An improved description of the near-pinchoff characteristics, high-voltage breakdown, and gain compression in the high-current region in the TOM is introduced. The new model accurately predicts the I-V, CV, bias-dependent S-parameter, waveform, power, and linearity characteristics of the MESFET.

A frequency dispersion model of GaAs MESFET for large-signal applications

Deficiencies in conventional frequency dispersion models of GaAs MESFET are addressed regarding their large-signal response. A new model which can accurately describes the large-signal dynamic properties is proposed. Only DC and scattering parameter data are required to extract the model parameters, which can be easily implemented into microwave circuit simulators in the macro circuit form. The validity of this model is demonstrated by comparing predicted pulsed I-V characteristics and power saturation characteristics with measured ones.

An improved DC model for circuit analysis programs for submicron GaAs MESFET's

An improved submicron GaAs MESFET model is presented which is suitable for nonlinear small-signal circuit designs. The Kacprzak-Materka model, which simulates the dc characteristics of large signal devices has been modified to predict the behavior of submicron devices. In this modification the concept of a shift in threshold voltage has been introduced. It has been shown that without taking into account the shift which is caused by the submicron geometry it is not possible to predict the device characteristics. Small-signal devices of different aspect ratio have been modeled with greater accuracy than that of other models. As far as possible we have determined the model parameters from the device physics and established the advantages of this approach over terminal methods. The modified model should be a useful tool for the designing of future integrated circuits with submicron gate length MESFET's.

A charge conserving capacitance model for GaAs MESFETs for CAD applications

A charge conserving capacitance model for GaAs MESFETs for Computer Aided Design (CAD) applications is presented. Simple analytical expressions for node charges were developed by integrating the sheet charge density over the gate length, which guarantees the charge conservation. The capacitances were defined by taking derivatives of the charges with respect to terminal voltages at the three nodes. The resulting, so-called transcapacitances are nonreciprocal in nature. Thus, we have defined a new equivalent circuit based on a total of nine transcapacitances, which can be organized as a 3 × 3 matrix. The model is valid both above and below threshold. Good agreement has been demonstrated with the experimental data.

A new charge conserving capacitance model for GaAs MESFET's

We present a new charge conserving capacitance model for Gallium-Arsenide (GaAs) metal semiconductor field effect transistors (MESFET's) based on the quasi-static approximation and a proper partitioning of the channel charge between the source and the drain terminals. A total of nine so-called transcapacitances were determined by taking derivatives of the various terminal charges with respect to the voltages at source, drain, and gate. The transcapacitances are nonreciprocal, i.e., C/sub ij//spl ne/C/sub ji/ when i/spl ne/j, and can be organized in a 3/spl times/3 matrix incorporating Kirchhoff's current law (charge conservation) and independence of reference. The present capacitance model is valid both above and below threshold, and shows good agreement with experimental data over a wide range of gate and drain biases. The model is analytical and suitable for implementation in circuit simulators.

The linear statistical d.c. model of GaAs MESFET using factor analysis : Lech Dobrzanski. Solid-State Electronics, 38, 2, 487 (1995)

The linear statistical d.c. model of GaAs MESFET using factor analysis : Lech Dobrzanski. Solid-State Electronics, 38, 2, 487 (1995)

Accurate large‐signal GaAs MESFET and HEMT modeling for power MMIC amplifier design

AbstractThis article describes, from an industrial user's point of view, how large‐signal GaAs MESFET and HEMT modeling can be done accurately and efficiently for power MMIC amplifier design. The method is based on commercially available CAD tools enhanced by in‐house software (e.g., small‐signal parameter extraction, generation of load‐pull contours). The Materka model is shown to predict accurately the large‐signal characteristics of GaAs MESFETs, but not of pseudomorphic HEMTs. For these devices, a modified Angelov model is found to be adequate. A method for determining the numerous large‐signal model parameters is presented. Model verification is achieved by comparing simulated and on‐wafer measured data like static I(V)‐characteristics, multiple bias S‐parameters, gain compression characteristics, and load‐pull contours. Results of device scaling and calculations of optimum load impedances are discussed. The close fit to the measured data proves that an excellent basis for large‐signal power MMIC design has been established.

A new analytical model of GaAs MESFET's

In this paper, a simple model for the calculation of the current—voltage characteristics of a short channel GaAs MESFET is first proposed. The new model can describe GaAs behavior for both high pinchoff and low pinchoff voltages. Test results show that it is more efficient and simpler than the previous models[1–7].

The linear statistical d.c. model of GaAs MESFET using factor analysis

The linear statistical model of the GaAs MESFET's current generator is obtained by means of factor analysis. Three different MESFET deterministic models are taken into account in the analysis: the Statz model (ST), the Materka-type model (MT) and a new proprietary model of MESFET with implanted channel (PLD). It is shown that statistical models obtained using factor analysis provide excellent generation of the multidimensional random variable representing the drain current of MESFET. The method of implementation of the statistical model into the SPICE program is presented. It is proved that for a strongly limited number of Monte Carlo analysis runs in that program, the statistical models considered in each case (ST, MT and PLD) enable good reconstruction of the empirical factor structure. The empirical correlation matrix of model parameters is not reconstructed exactly by statistical modelling, but values of correlation matrix elements obtained from simulated data are within the confidence intervals for the small sample. This paper proves that a formal approach to statistical modelling using factor analysis is the right path to follow, in spite of the fact, that CAD systems (PSpice[MicroSim Corp.], Microwave Harmonica[Compact Software]) are not designed properly for generation of the multidimensional random variable. It is obvious that further progress in implementation of statistical methods in CAD software is required. Furthermore, a new approach to the MESFET's d.c. model is presented. The separate functions, describing the linear as well as the saturated region of MESFET output characteristics, are combined in the single equation. This way of modelling is particularly suitable for transistors with an implanted channel.

An independently matched parameter SPICE model for GaAs MESFET's

A GaAs MESFET model is presented that addresses the modeling problem arising from the discrepancy between the derivatives of the dc current and the measured small signal parameters of a GaAs MESFET. This discrepancy traditionally required the user of a non-linear circuit analysis program such as SPICE to trade off the accuracy between the dc analysis and ac analysis. This paper addresses this problem and leads to a solution that completely eliminates the need for such a trade off. Two additional nodes are incorporated into the SPICE MESFET model by providing two extra conducting paths necessary to reconcile the aforementioned discrepancies and to keep the equations self-consistent. In addition, the model allows the user to select different sets of model parameters to independently match I/sub ds/, g/sub m/, and g/sub ds/, An integration scheme to transform the new model back to a 3/spl times/3 Y-matrix is employed to accelerate the simulation speed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>