On Wafer RF Testing Characterizes Current SAG on GaAs MESFETs

A relatively simple measurement technique aids in MESFET characterization of the phenomena known as current sag. Current sag is described as a decrease in the net DC drain current when low to medium RF power is applied. These on-wafer measurements are taken on an ATN active load pull system. The output impedance can be swept from a short to an open along the real axis of the Smith chart to understand the relationship between load line and current sag.