Improved linearity in solid-state power amplifiers for multi-carrier communication systems.

摘要

A three-stage pseudomorphic High Electron Mobility Transistor Ka-band power amplifier with a 12 dBc improvement in linearity for a Local Multipoint Distribution System (LMDS) has been demonstrated. The amplifier design uses an enhanced pHEMT cell which has a reduced gate pitch and wide gate recess. This improves the amplifier's gain by 6 dB and output power by 2.54 dB. A greater than 1:2 stage to stage FET gate periphery ratio was used to reduce the third-order spurious response produced by the first two stages. Each stage of the amplifier was load impedance matched for maximum output power and minimum third-order intermodulation ratio (IMR3). On-wafer and fixtured measurements show that at 28 GHz under two-tone input stimulus, the amplifier has an output third-order intercept (OTOI) of 37 dB.