Gain compression in GaN HEMT amplifiers

Abstract

Volterra series analysis is used to determine linear and nonlinear gain, output power of a GaN HEMT amplifier. Gain compression defined as the difference between linear and nonlinear gain is reported for varying temperatures. Measured 1-dB gain compression of 17.5 dBm for a 1/spl times/500 /spl mu/m Al/sub 0.15/Ga/sub 0.85/N/GaN HEMT at 300 K and at 2 GHz is in excellent agreement with the calculated value of 17 dBm. With the operating frequency increasing from 1 GHz to 6 GHz the 1-dB gain compression point decreases from 20.5 dBm to 13.8 dBm at 300 K. At 2 GHz the 1-dB gain compression point decreases from 17.5 dBm at 300 K to 6.5 dBm at 600 K.