Sensitivity Of The RF Performance Of GaAs Power FETs To Process-dependent Parameters

Abstract

In recent years, the rapid growth of the Monolithic Microwave Integrated Circuits (MMICs) market has spurred considerable interest in large-signal modeling of GaAs MESFETs. An accurate Computer Aided Design (CAD) tool for the GaAs MESFET is important to the economic viability of MMIC technology. The design of microwave circuits for small-signal applications has substantially benefited from linear characterization techniques such as S-parameters. It is difficult, however, to apply this methodology to the design of microwave circuits for high-power applications in which nonlinear effects are dominant. There are three empirical techniques presently used in the characterization of power FETs: 1) the load pull method[ll, 2) "large-signal S-parameter" measurement[2], and 3 ) characterization by means of small signal S-parameters measured at different bias voltages [ 3 ] . These empirical methods, however, require that the device be fabricated prior to large signal characterization. Therefore, unless a systematic, controlled experiment on several devices is performed, little information can be gained from these techniques about the relation between large signal performance and device parameters.