A 77-GHz to 90-GHz bidirectional amplifier for half-duplex front-ends

A W-band, bidirectional constructive wave amplifier is proposed that eliminates the need for a T/R switch. The amplifier allows amplification of either a forward or backward traveling wave. The measured amplifier has a peak gain of 16 dB and bandwidth of 14.5 GHz at 90 GHz and the center frequency can be electronically controlled between 77 and 90 GHz. The circuit is fabricated in a 0.12 μm SiGe BiCMOS process, occupies an area of 0.47 mm
²
, and consumes approximately 32 mA from a 2 V supply. To the author's knowledge, this is the first W-band, bidirectional amplifier in a silicon/silicon-germanium process.