A 2-Way W-Band Power Amplifier With an Isolated Combining Output Network for Power Back-Off Efficiency Enhancement in 16-nm FinFet Technology

This letter introduces a W-Band sequential power amplifier (PA) (Lehmann and Knoechel, 2008) with a novel output network designed to minimize passive and combiner losses, while reducing the overall footprint compared to conventional sequential and Doherty PAs (Doherty, 1936). An isolated output combiner sums two PAs operating in two different modes: 1) the main amplifier operates in class AB and 2) the auxiliary amplifier operates in class C. The measured PA achieves a saturated output power $(\mathbf {P_{\mathrm { sat}}})$ of 13 dBm and a gain of 12.5 dB with 3-dB bandwidth (BW) from 79.5 to 94.5 GHz. Additionally, it demonstrates a peak power-added efficiency (PAE) of 19.4% and a 14.6% PAE at 6-dB power back-off (PBO) at 87.5 GHz. Furthermore, the PA achieves a data rate of 12 Gb/s for a 16QAM signal with an average output power of 5 dBm, an average PAE of 10%, and an EVM (RMS) of -20 dB. The PA was fabricated in 16-nm FinFet technology with core area of 0.15 mm2. To the authors’ knowledge, this PA has the highest PAE at 6-dB PBO for CMOS PAs operating in the W-Band.