Optimization of the noise resistance of MESFET's and hemt's for CAD of microwave low-noise amplifiers

摘要

Among the noise parameters expressed in the reflection coefficient form ( Fo, IFOI,ud/Fo and rn ), the noise resistance rn is of critical importance lo the design of low-noiseudreceivers. Very low values of rn allow for optimizing the performance of broad bandudamplifiers in receiver front-ends.udWe here present an analysis performed on typical circuit models of FET's which was aimed atudassessing the key elements influencing the behavior of rn at microwave frequencies.udWe found that the noise performance can be improved by tuning the value of the input (gate,udsource) inductances which are responsible of the U shaped curves typically observed for rn inudMESFET's and HEMT's.