An Ultracompact Bidirectional CMOS Gate-Switching Cascode Amplifier for Millimeter-Wave Transceiver Front End

This article presents an ultracompact single-channel bidirectional amplifier for millimeter-wave front end. The bidirectional gate-switching cascode amplifier core is proposed to reduce the leakage current in transmitting (TX) and receiving (RX) modes to enhance TX output power and gain performance as well as RX input matching with compact size. Meanwhile, a tri-coil coupling technique is leveraged to expand the bandwidth and improve the stability of the amplifier. As a proof of concept, a two-stage bidirectional cascode amplifier with gate switches is implemented in a 40-nm bulk CMOS process. In the measurement, the proposed amplifier achieved 3-dB bandwidth from 52 to 67 GHz, saturated output power of 15.24 dBm, OP1 dB of 12.79 dBm, peak PAE of 9.35% at 60 GHz in the TX mode, and 78 mW from a dc supply of 1.5 V in the RX mode. The core circuit occupies an area of only 0.08 mm2.