Dynamic Gate Bias Technique for Improved Linearity of GaN HFET Power Amplifiers

This work demonstrates a significant reduction in third order intermodulation distortion of an AlGaN/GaN HFET using the dynamic gate bias technique. In this technique the gate bias and thus the gain of the transistor is adjusted in accordance with the instantaneous envelope of the input signal to minimize AM-AM distortion while maintaining high efficiency of deep class AB operation. A 10 dB reduction in IM3 was measured in two-tone tests, centered at 815 MHz.