A Digital Transmitter Based on Class-G Quadrature Switched-Capacitor Power Amplifier with Efficiency Enhancement and Linearization Techniques

In the era of 5G communication that should support a high data rate for mobile subscribers, the transmitter systems should have a very high linearity and a wide bandwidth to meet the huge demand in faster communication speed and more data traffic. Moreover, the energy efficiency is very important for the extended battery lifetime and user experience for mobile subscribers. A digital transmitter based on switched capacitor power amplifier (SCPA) shows an excellent accuracy and good system efficiency required for future communication system. Digital transmitter architectures will be discussed especially focused on digital SCPA. The prototype in 65nm CMOS achieves peak output power and PAE of 30.1dBm and 37.0%, respectively. For 802.11g 64-QAM OFDM signal with 10.6dB PAPR (20MHz single-carrier 256-QAM signal with 7.6dB PAPR), it demonstrates an average output power of 19.5dBm (22.5dBm) and PAE of 14.7% (18.3%), while achieving EVM of -40.7dB (-40.3dB).