A High Power and Low Distortion AlGaAs Hetero MESFET with a Graded Pulse-doped Channel for Base Station Applications

This paper reports on high power GaAs MESFET for base station applications, which has been improved over conventional GaAs MESFET in several aspects. High uniformity and high yield are achieved with a planar structure by using an n+ implantation and rapid thermal anneal (RTA) process rather than a recess process. Breakdown voltage and gate leak current are improved by the insertion of an AlGaAs-cap layer for usage in high drain voltage operations more than 10V. A graded pulse-doped channel is an active layer in which doping concentration increases exponentially toward the buffer layer, prevents output power deviation for bias drain current The AlGaAs hetero MESFET shows high gain (18dB), high output power (450mW/mm), and low intermodulation distortion (IP3=40dBm) at 1.9GH, which demonstrates excellent performance for digital wireless base station applications.