A PMOS mm-wave power amplifier at 77 GHz with 90 mW output power and 24% efficiency

In deeply scaled CMOS processes with gate lengths below 40 nm the analog performance of NMOS and PMOS FETs are comparable. At the same time PMOS FETs can typically operate under higher operating voltages than NMOS devices. In this paper, we present the first millimeter-wave power amplifier exclusively employing PMOS. The single stage, 3-stack power amplifier operates at 65 - 92 GHz with more than 35% fractional bandwidth and 12 dB gain. At 78 GHz, the PA achieves a maximum output power of 19.6 dBm and PAE of 18% with class-A bias, and 18.7 dBm and 24% PAE with class-AB bias. The PA has been fabricated in 32 nm CMOS SOI process and occupies 440 μm × 280 μm area (only 0.05 mm2 excluding pads). To the authors' knowledge this PA achieves the highest efficiency for any silicon PA in the 60-90 GHz frequency band. The output power is also the best reported in silicon for this frequency range, for amplifiers that do not use elaborate power-combining approaches.