A 50 GHz feedback amplifier with AlInAs/GaInAs transferred-substrate HBT

Transferred-substrate heterojunction bipolar transistors (HBTs) have very high f/sub max/ and are potential candidates for very high-speed integrated circuit applications. We report a wideband amplifier with AlInAs/GaInAs transferred-substrate HBTs. A simple Darlington configuration with resistive feedback is used and has 13 dB gain, 50 GHz 3-dB bandwidth. This is the first demonstration of a integrated circuit in the transferred-substrate HBT process.