A 1.8GHz stacked power amplifier in 45nm CMOS SOI technology with substrate-transferred to AlN

A 1.8GHz power amplifier (PA) is implemented with a stack of 16 dynamically-biased thin-oxide transistors (tox = 1.16nm) in a standard 45nm CMOS SOI process. The stack configuration increases the overall breakdown voltage as well as the output impedance. The conductive Si substrate of the PA fabricated in a standard 45nm CMOS SOI process is etched and replaced by Aluminum Nitride (AlN) substrate to reduce the adverse effect of parasitic capacitances. The PA delivers a saturated output power (PSAT) of 26.5 dBm and a peak power added efficiency (PAE) of 19% at 1.8GHz when biased with high supply voltage (VDD = 12V) and low drain current for satisfying high-reliability requirements. The performance is comparable with reported PAs despite using very low-breakdown voltage transistors.