19.1 Receiver with >20MHz bandwidth self-interference cancellation suitable for FDD, co-existence and full-duplex applications

Abstract

In this paper, a 0.8-to-1.4GHz receiver with a tunable, reconfigurable RF SI canceller at the RX input is presented that supports >20MHz cancellation BW across a variety of antenna interfaces (nearly 10× improvement over a conventional canceller). This is accomplished by (i) a bank of tunable, reconfigurable 2nd-order high-Q RF bandpass filters in the canceller to emulate the antenna interface isolation (essentially RF frequency-domain equalization), and (ii) a linear N-path Gm-C filter implementation with embedded variable attenuation and phase shifting. For FDD, SIC enhances effective OOB IIP3 and IIP2 to +25-27d Bm and +90d Bm respectively. For SC-FD, SIC eliminates RX gain compression for as high as -8 dBm of peak in-band SI, and enhances effective in-band IIP3 and IIP2 by 22dB and 58 dB.