Comparison of pMOS and nMOS 28 GHz high efficiency linear power amplifiers in 45 nm CMOS SOI

High efficiency, compact CMOS power amplifiers (PAs) based on nMOS and pMOS transistors in 45 nm CMOS SOI technology for Ka-band applications are presented. Both the nMOS and pMOS amplifiers use 2-stack power devices in order to increase the maximum output voltage swing. Both the nMOS and pMOS PAs have peak small signal gain of about 13 dB, and demonstrate more than 40% peak PAE, with 18.9 dBm saturated output power for the nMOS and 17.8 dBm for the pMOS (when measured at the same drain bias voltage.) With a 64-QAM OFDM signal with 800MHz bandwidth, the nMOS PA achieves EVM = 5.5% with average output power of P_out = 9.8 dBm and average PAE = 14.8%. We show that the pMOS amplifiers are able to withstand higher drain bias voltages than their nMOS counterparts. The amplifiers have compact dimensions and occupy 0.18 mm² of active area.