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

Abstract

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.