A 1.5-3 GHz Quadrature Balanced Switched-Capacitor CMOS Transmitter for Full Duplex and Half Duplex Wireless Systems

This work proposes a reconfigurable multi-mode digital transmitter based on quadrature balanced switched-capacitor power amplifiers (QB-SCPA), supporting both full duplex (FD) and half duplex (HD) operation. The QB-SCPA architecture provides built-in passive transmit-receive isolation along with an embedded and wideband self-interference cancellation (SIC) signal injection mechanism. In addition, it allows for phase noise suppression at the RX through clock sharing and exhibits excellent TX and RX linearity. In FD mode, we demonstrate >72 dB of total TX-RX isolation over a BW larger than 1 GHz at 21 dBm peak TX power with 17.4% system PAE. In HD TX mode, the system achieves 23 dBm peak TX power with 26.5% PAE.