RF Performance

Summary

High electron mobility transistors (HEMT), using GaN as a semiconductor material, are available from Microchip, MACOM, NXP, Integra, and Qorvo, among others. All these transistors are depletion‐mode, which is not as limiting for RF power amplifiers as it is for switching converters. This is because the potential of device failure upon power up, due to the short condition, can be mitigated easily in the RF design, which is not the case for a switching converter. Depletion‐mode transistors require additional circuitry for gate circuit biasing, due to the negative gate voltage requirements to regulate the drain current, which is also viewed as a disadvantage in cases where enhancement‐mode devices are an option.