A quadrature switched capacitor power amplifier in 65nm CMOS

This paper presents a quadrature switched-capacitor power amplifier (SCPA) that achieves similar output power and efficiency as polar/EER based digital PAs. It combines in-phase (I) and quadrature (Q) signals on a shared capacitor array in the charge domain. The SCPA utilizes a class-G dual-supply architecture to improve efficiency at backoff. This counteracts losses associated with the signal combination. Unlike polar/EER counterparts, the quadrature SCPA requires no wideband phase modulator or delay matching circuitry. The SCPA delivers a peak output power of 20.5 dBm with a peak PAE of 20%.