Wideband Dual-Injection Path Self-Interference Cancellation Architecture for Full-Duplex Transceivers

A transceiver front end including a dual-injection path self-interference (SI) cancellation architecture is proposed for use in wideband full-duplex networks. The SI cancellation circuitry is implemented using: 1) one feedforward cancellation path containing a five-tap analog adaptive finite-impulse response (FIR) filter between the transmitter (TX) output and the receiver (RX) input; 2) a second baseband (BB) cancellation path containing a 14-tap low-frequency FIR filter with a point of injection at the RX BB output; 3) a phase noise cancellation method that suppresses the reciprocal mixing products associated with the downconversion in the BB cancellation path for the TX SI signal; and 4) an integrated noise cancelling power amplifier (PA). A prototype of 40-nm TSMC device was fabricated, which demonstrates more than 50-dB SI cancellation over 42-MHz bandwidth and a 10-dB attenuation of TX SI phase noise in the RX signal path. The two cancelling filters dissipate 11.5 mW, with a measured P
_{-1 dB}
and IIP
₃
of 27/26.5 and 36/34.5 dBm, respectively. The RX noise figure is degraded by less than 1.55 dB, when both cancellers are enabled. The PA has a measured output of P
_{-1 dB}
/P
_sat
of 25.1/26.5 dBm, respectively. The total chip die area is 3.5 mm
²
with an overall transceiver power consumption of 49 mW, excluding the integrated PA.