Microwave performance of AlGaAs/InGaAs pseudomorphic HEMTs with tuneable field-plate voltage

Abstract

GaAs-based pseudomorphic high electron mobility transistors (pHEMTs) in which the field-plate (FP) metal is supplied with various biases were developed and evaluated experimentally to determine their microwave and power performance. To minimize the strong electric field between drain and gate terminals, the field-plate technique in pHEMT fabrication was used in the past. In this study, the device breakdown voltage was found to reduce with the voltage of the field-plate metal (VFP). Owing to the depth modulation of the field-plate-induced depletion region at various field-plate biases, the device dc, RF, flicker noise and power performance were also influenced by tuneable VFP. This technique is easy to apply, based on standard pHEMT fabrication, and especially attractive for high-linearity power amplifiers by connecting VFP to negative bias.