$Q$ -Band Spatially Combined Power Amplifier Arrays in 45-nm CMOS SOI

This paper reports 45-GHz power amplifier (PA) arrays implemented in 45-nm CMOS silicon-on-insulator, coupled to antenna arrays to enable free-space power combining. A single CMOS chip (2.5 × 4.5 mm²) containing eight-unit PAs was developed and its output was fed to a 2 × 2 array of differentially fed patch antennas on a printed circuit board. This array provided an equivalent isotropic radiated power (EIRP) of 40 dBm at 45 GHz with 28 dBm of total RF power generated by the chip. A larger array, composed of four CMOS chips and feeding a 2 × 8 array of antennas, was shown to deliver an EIRP of 50 dBm at 45 GHz, while generating a total RF power of 33 dBm together with an antenna array gain of 17 dB. The dc power consumptions for the 2 × 2 and the 2 × 8 arrays were 4.9 and 18 W, respectively, with estimated peak power-added efficiencies of 13.5% and 10.7%.