Study of self-heating in GaAs pHEMTs using pulsed I-V Analysis

A pulsed I-V thermal resistance R_th measurement method is formulated and applied on-wafer to a GaAs MMIC pHEMT. An investigation of device dispersion phenomena assesses their impact on the measurement. It is found that performing the R_th measurement using two quiescent bias points in close proximity (situated beyond the knee voltage yet prior to drain voltages that result in significant levels of gate leakage due to impact ionization) improves the accuracy of the method. Extraction of thermal coefficients characterizes the drain current reduction due to heating, allowing for an efficient calculation of R_th with improved precision.