A 52-dB Self-Interference Rejection Receiver using RF Code-Domain Signal Processing

Abstract

This paper presents a code-domain receiver (RX) for simultaneous transmit and receive (STAR) applications. The RX achieves 52 dB of transmitter self-interference (TX SI) rejection through the application of direct sequence spread spectrum (DSSS) techniques at the antenna. The rejection is achieved through a cascade of code notch (CN) and code pass (CP) filters operating at the same center frequency. The integrated RX is tunable from 0.25 GHz to 1.25 GHz with 39 dB of gain at 1 GHz. The RX is implemented in a 45-nm CMOS SOI process and occupies an area of 2.6 mm2 including the filters, a low noise amplifier (LNA), and baseband circuits.