The CMOS switched-capacitor power amplifier (SCPA) architecture was disclosed in 2011. It enabled the design of fully-integrated radio frequency (RF) transmitters with much higher power-added efficiency (PAE) than previous approaches. Herein, new techniques are introduced that increase SCPA linearity. Specifically, a baseband harmonicrejection (BBHR) technique is used to minimize the counter third-order intermodulation products (C-IM3). Also, using a Wilkinson combiner, the cross-coupling between two subSCPAs is isolated to enable a linear harmonic-rejection summation. With the proposed topology, the linearity is improved significantly compared to a conventional I/Q-sharing SCPA. More specifically, the C-IM3 is reduced by ~25 dB with a single-tone input and by ~22 dB with modulated signal。