MODELING AND PERFORMANCE OF A 100-ELEMENT PHEMT GRID AMPLIFIER

A 100-element hybrid grid amplifier has been fabricated, The active de vices in the grid are custom-made pseudomorphic high electron mobility transistor (pHEMT) differential-pair chips, We present a model for ga in analysis and compare measurements with theory. The grid includes st abilizing resistors in the gate, Measurements show the grid has a peak gain of 10 dB when tuned for 10 GHz and a gain of 12 dB when tuned fo r 9 GHz, The maximum 3-dB bandwidth is 15% at 9 GHz, The minimum noise figure is 3 db, The maximum saturated output power is 3.7 W, with a p eak power-added efficiency of 12%, These results are a significant imp rovement over previous grid amplifiers based on heterojunction bipolar transistors (HBT's).