Highly-Linear Integrated Magnetic-Free Circulator-Receiver For Full-Duplex Wireless

A fundamental challenge of full-duplex (FD) wireless [1] is the implementation of low-cost, small-form-factor, integrated shared-antenna (ANT) interfaces with low loss, low noise, high TX-RX isolation, and large TX power handling. Providing more TX-RX isolation in the ANT interface that is robust to environmental variations lowers the self-interference cancellation (SIC) and dynamic range required in the RF, analog baseband (BB), and digital domains. Reciprocal shared-ANT interfaces, such as electrical-balance duplexers [2], fundamentally feature at least 3dB loss (practically u003e4dB). A non-reciprocal active shared-ANT duplexing scheme was demonstrated in [3], but such active approaches are limited in their maximum supported TX power (−17.3dBm in [3] limited by RX compression) and noise performance. An integrated FD RX with a magnetic-free non-reciprocal passive circulator was demonstrated in [4]. Despite the circulatoru0027s low loss and relatively high linearity, the RX could only handle up to −7dBm TX power due to limited circulator isolation and RX LNA linearity. NF under cancellation was also as high as 10.9dB.