An FDD Wireless Diversity Receiver With Transmitter Leakage Cancellation in Transmit and Receive Bands

Abstract

Antenna-coupling group delay limits the cancellation bandwidth of conventional self-interference cancellers (SICs), making it difficult to ensure isolation in both transmit (TX) and receive (RX) bands. Isolation over both bands is achieved in the dual-path receiver architecture proposed in this paper. The main path consists of a highly linear current-mode RX with a passive RF SIC. The auxiliary path implements a notch in the TX band followed by an adaptive digital equalizer whose output is used to suppress the TX noise leakage in the RX band. The main and auxiliary receiver prototypes, implemented in 28-nm CMOS technology, operate between 1 and 2 GHz, occupy an area of 0.51 and 0.12 mm2, and have a power dissipation of 32-40 and 26-64 mW, respectively. The stand-alone RX has a noise figure (NF) of 4-5 dB and an out-of-band IIP3 of 18 dBm. Turning on the passive canceller results in an effective IIP3 of 25-29 dBm and a degradation of the NF of less than 0.8 dB. Thanks to its high dynamic range, the auxiliary path suppresses the TX noise by >29 dB while degrading the RX NF by only 1 dB at 23-dBm TX output power.