A Q-band monolithic linear amplifier using AlGaAs/GaAs HBT's

The authors report on a Q-band monolithic heterojunction bipolar transistor (HBT) amplifier demonstrating high gain, efficiency, excellent linearity, and low added phase noise. The amplifier used 40 /spl mu/m/sup 2/ CB-HBTs in a balanced configuration. The monolithic microwave integrated circuit (MMIC) amplifier showed a peak gain of 13.5 dB at 38 GHz and a 3 dB bandwidth of 10 GHz. Under class-A bias conditions, the circuit exhibited P/sub 1 dB/ higher than 15 dBm from 35-41.5 GHz and a peak PAE of 32% at 35 GHz. Two-tone tests showed an IP/sub 3/ of 30 dBm at 44 GHz and IMD/sub 3/ ratios better than 20 dBc at 1-dB gain compression point. Amplifier phase noise measurement showed added phase noise of -148 dBc/Hz at 10 kHz away from the carrier at P/sub 1/ /sub dB/. This circuit demonstrates a great potential for the HBT MMIC's for MM-wave high-efficiency linear applications.