Characterization Of MESFETs Research Articles

Condition number for reliable microwave transistor modeling

An appropriate procedure enabling the evaluation of the sensitivity of a MESFET small-signal model given unavoidable measurement errors is presented in the first section of this article. This technique, which is based on calculation of the condition number, has been applied to an NE 76000 MESFET device. The results obtained enabled us to highlight the difficulties of an accurate MESFET characterization and to predict the equivalent-circuit element errors. In the second part, we introduce a new approach that makes it possible to reduce the sensitivity of the parameters of the model. When applied to the same transistor, this approach enables us to reduce the sensitivity of the model of 30% on average. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 174–181, 2004.

Microwave power MESFET on 4H-SiC

We present static and microwave characterization of MESFETs processed on n+ 4H-SiC wafers supplied by Cree Research. An eight-level technology including airbridge interconnections has been performed. Transistors with total gate width up to 6 mm and 1.2 μm gate length optically designed are obtained. High breakdown voltage (up to 140 V) and high drain current (up to 0.7 A) show the high power capability of the transistors. RF characterization was performed. Because of the use of a conductive substrate, parasitic capacitances account for the relatively low values of fT and fmax (4 and 9 GHz, respectively). Power measurements were carried out at 1 and 2 GHz in cw. Output powers up to 1.7 W mm−1 were measured with a power added efficiency of 37% at 2 GHz.

Accurate noise characterization of short gate length GaAs mesfets and hemts for use in low‐noise optical receivers

AbstractAccurate noise characterization of MESFETs and HEMTs is required for the design of high‐frequency optical receivers. Here we consider a technique that extracts the intrinsic noise parameters P, R, C from measured noise data. Novel analytic expressions are presented as well as results that prove the validity of the technique. © 1993 John Wiley & sons, Inc.

GaAs MESFET characterization using least squares approximation by rational functions

The authors propose a method of characterizing active devices such as the FET by describing S-parameters with a set of rational functions of angular frequency. The set of rational functions is uniquely determined by only 27 coefficients, while the conventional method using tabulated S-parameters requires eight times the number of sampling points (a typical case might require 404 data points in floating-point notation). This drastically reduces the database size required to give adequate information for circuit design. A method for determining the equivalent circuit is described. Since the equivalent circuit is determined from the set of rational functions, no additional measurements are needed to determine extrinsic elements. In conventional methods, selection of initial values affects the final results. In the present method, reliable initial values are extracted from the rational functions' coefficients. The calculated S-parameters of three GaAs MESFETs having different gate widths agree closely with those measured by wafer-probe. >

Complete characterization of MESFET Ids nonlinearities for intermodulation analysis

AbstractThis work shows that an accurate characterization of the nonlinear distortion of a GaAs MESFET, does not allow the common approach of splitting the Ids, (Vds, Vds) current in two voltage‐dependent nonlinear current sources, Gm(Vgs) and Gdx(Vds). It is shown that the cross terms of the Ids Taylor series expansion can give an important contribution to the MESFETs intermodulanon distortion behavior. A laboratory procedure for the complete characterization of that element is given. © 1992 John Wiley & Sons, Inc.