A review of recent and current work on microwave FET's and amplifiers is presented, and an extensive bibliography of recent articles is appended (250 references). First, the various FET structures (MRSFET's, JFET's, and IGFET's) and their performances are reviewed. Second, the principle of operation is outlined for Si- and GaAs-MESFET's; the basic device physics, equivalent circuit, high-frequency limitations, and noise behavior are treated. Third, the design principles and performance of microwave MESFET amplifiers are summarized.

Microwave Field-Effect Transistors--1976

Techniques for large signal GaAs MESFET oscillator design are described which do not require repeated large signal measurement. In the first technique, small signal S-parameter measurements are used with a computer program to compute the packaged and mounted device equivalent circuit. Large signal measurements are made to determine a mathematical relationship between only those parameters which vary under large signal conditions. These relationships are included in the computer program. Then, once the equivalent circuit has been computed from the small signal S-parameter measurements, those parameters varying under large signals are incrementally altered until large signal S parameters are obtained which correspond to maximum oscillator output power. These values are used to calculate embedding element values for six oscillator topologies. A coaxial cavity FET oscillator was built and tested using the large signal design theory, and it substantially verified the design technique. The second design technique is based on the fact that S/sub 21/ varied more than other S parameters under large signals. By making design calculations based on S/sub 21/ reduced to the point corresponding to maximum oscillator power, it was possible to get usable design information for an FET oscillator.

Large Signal GaAs MESFET Oscillator Design

A multioctave model of GaAs dual gate MESFET's is presented. It consists of 28 frequency independent elements and is valid between 2 and 11 GHz. Dual gate FET's with and without intergate ohmic contact have been considered. The modeling method utilized consists in separate dc and HF characterization and equivalent circuit determination of the active device parts in their actual bias conditions. Thereby, two goals are obtained : a) The topology of the overall model can be derived from well-known simpler, partial ones; and b) the starting values of optimization are precise enough to allow reliable physical solutions.

Microwave Wide-Band Model of GaAs Dual Gate MESFET's

This paper reviews the state of the art of power GaAs MESFET's. Items that will be covered are the operating principles of the device from a material and geometric point of view, the design, fabrication sequences, and material structures used by various laboratories, the factors identified as important to power by workers in the field the performance of the device in terms of frequency effects, power per unit gate-width effects, scaling from small to large gate-width devices, and voltage effects. In addition, the circuit applications of GaAs FET's will be briefly discussed.

GaAs Power MESFET's: Design, Fabrication, and Performance

After a brief review of the noise-generating mechanisms intrinsic to the GaAs FET, an enumeration is given of the various parasitic elements associated with the FET which affect the noise performance. These elements include, among others, the gate metallisation and source contact resistances, drain-gate feedback capacitance, and source lead inductance. Numerous graphs are presented to illustrate the effects of these elements and the various design parameters on the noise performance. A comparison is made between the theoretically predicted and the measured noise performance of microwave GaAs FET's. The best state-of-the-art noise performance as reported by various laboratories is illustrated graphically for single-stage and multistage FET amplifiers. Finally, some speculation is attempted in regard to the possible reductions in noise figure to be expected from technological and design improvements of GaAs FET's.

Noise performance of gallium arsenide field-effect transistors

A new equivalent circuit is given for the GaAs m.e.s.f.e.t., which includes resistive loss in the feed back elements. The circuit values are given for several 1 μm-gate GaAs m.e.s.f.e.t.s. A method for fitting s12 to the measured data is described. Finally, the gain and stability factor of several GaAs m.e.s.f.e.t.s. are extrapolated to 24 GHz from the present model.

G.D. Vendelin

Papers

Circuit model for the GaAs m.e.s.f.e.t. valid to 12 GHz