Abstract

Cryogenic on-wafer load-pull measurements are performed on GaAs MESFET (Lg=0.6um, W=300um and Lg=1.0nm, W=300um) power devices at 300K, 200K and 15K to demonstrate their performance improvement in output power and power-added efficiency when operated at reduced lattice temperatures. The power measurements were achieved at optimal bias condition to take into account the positive Temperature Coefficient (TC) that the On Breakdown Voltage exhibits. Additionally, an empirical temperature-dependent large-signal model valid to 18GHz is developed using experimental S-parameters and DC measurements to correlate actual load-pull measurements from 300K to 15K and to understand the performance improvements in output power and power-added efficiency. The model is also used to correlate the effect of the TC of Breakdown Voltage to power measurements.