A Novel Concept using Derivative Superposition at the Device-Level to Reduce Linearity Sensitivity to Bias in N-polar GaN MISHEMT

Abstract

N-polar GaN MISHEMTs have recently demonstrated excellent power performance and power-added efficiency at 94 GHz [1] . At mm-wave frequencies and high data rates, the linearity of an RF transistor is an important requisite. Third-order non-linearities lead to undesirable effects such as in-band signal distortion and are therefore important to control. This study presents a novel device concept to enhance the linearity of N-polar GaN MISHEMTs at millimeter wave frequencies (30 GHz and beyond) for low-power receiver application. We have recently reported linearity data on N-polar GaN MISHEMTs with OIP3/P DC of 11.4 dB [2] and 15 dB [3] at 30 GHz. We have observed in [2] , [3] that the peak linearity performance is limited to a narrow input-bias range, resulting in susceptibility to process and temperature variations. Therefore, we explore a novel device structure that can provide its best OIP3/P DC performance over a wide input-bias range.