An electrical-balance duplexer for in-band full-duplex with <-85dBm in-band distortion at +10dBm TX-power

When using electrical-balance duplexers (EBDs) to provide RF self-interference cancellation for in-band full-duplex, in-band distortion produced by nonlinear CMOS switches in the duplexer cause distortion that limits the headroom for additional self-interference cancellation in subsequent cancellation schemes in the transceiver. A prototype EBD is fabricated in 0.18μm SOI CMOS to investigate the dynamic range limitations of a transceiver architecture for next-generation wireless systems that supports in-band full-duplex and legacy FDD. Measurements show -85dBm in-band distortion at +10dBm TX input power, enough for short-range links at 10MHz BW.