Switched-Capacitor RF Power Amplifiers: A Review of Efficiency and Linearity Considerations

This paper reviews the recent advancements in the realization of all-digital switched-capacitor power amplifiers (SCPA), and proposes a method for comparison between the different transmitter (Tx) architectures based on circuit level simulations and Matlab signal processing using actual Wi-Fi 802.11ac OFDM signals. The SCPA topologies and I/Q combining approaches are analysed in view of their power-added efficiency (PAE), linearity and implementation complexity. The analysis method shows that I/Q combining techniques can have comparable PAE performance to polar architectures per error vector magnitude (EVM) levels, while requiring lower phase synchronization bandwidth and implementation effort.