An efficient small signal parameters estimation technique for submicron GaAs MESFET's

Abstract

Inthis investigation asoftware tool hasbeen developed whichcomputes AC behavior ofmm- wavelength GaAsMetalSemiconductor FieldEffect Transistors (MESFETs)by usingobserved DC characteristics. TheDC characteristics ofaMESFET arefirst simulated byusing thefabrication parameters ofthedevice whicharethencompared withthe observed response. Onceagoodmatchisattained by minimizing RMS errorvalues, thedeviceAC parameters arethenevaluated by employing the observed DC data. Thetechnique ensures thatthere should benodiscrepancy inthedevice smallsignal parameters caused byeither theinterfacial layer atthe Schottky barrier ortheshort channel effects whichare normally there insubmicron devices. Thevalidity ofthe developed technique isdemonstrated bycomparing the estimated values ofintrinsic small signal parameters of aMESFETwiththeobserved ones. Forthis purpose, theintrinsic small signal parameters values havebeen calculated fromtheobserved S-parameters ofthedevice byusing ade-embedding technique. Ithasbeenshown thatanaccurate DC modeling isakeytopredict an accurate AC small signal equivalent circuit ofadevice. Furthermore, thedeveloped technique ishighly time efficient because itusesDC measurements forthe estimation ofACparameters ofaGaAsMESFET.