9.8 Receiver with integrated magnetic-free N-path-filter-based non-reciprocal circulator and baseband self-interference cancellation for full-duplex wireless

Full-duplex (FD) is an emergent wireless communication paradigm where the transmitter (TX) and the receiver (RX) operate at the same time and at the same frequency. The fundamental challenge with FD is the tremendous amount of TX self-interference (SI) at the RX. Low-power applications relax FD system requirements [1], but an FD system with -6dBm transmit power, 10MHz signal bandwidth and 12dB NF budget still requires 86dB of SI suppression to reach the -92dBm noise floor. Recent research has focused on techniques for integrated self-interference cancellation (SIC) in FD receivers [1-3]. Open challenges include achieving the challenging levels of SIC through multi-domain cancellation, and low-loss shared-antenna (ANT) interfaces with high TX-to-RX isolation. Sharedantenna interfaces enable compact form factor, translate easily to MIMO, and ease system design through channel reciprocity.