Transformer-Combining Digital PA with Efficiency Peaking at 0, −6, and −12 dB Backoff in 32nm CMOS

A digital switched-capacitor transformer-combining power amplifier (SCPA) that uses load modulation to achieve efficiency peaking at 0, −6, and −12 dB backoff levels is beneficial for signals with high peak-to-average power ratios (PAPR). The PA uses a specific switched-capacitor cell design and turn-on sequence, that, contrary to the prior art, ensures correct-by-construction load modulation at backoff, even in the presence of practical transformer non-idealities. The PA has been implemented in 32nm CMOS and tested as part of a complete WiFi polar transmitter.