A 5GHz to 6GHz CMOS transmitter for full-duplex wireless with wideband digital cancellation

This paper presents a quadrature balanced transmitter, assisted by a digital equalization and predistortion self-interference cancellation technique for Full-Duplex wireless applications. An analysis of design trade-offs between low receiver (Rx) loss and high transmitter (Tx) efficiency is laid out and demonstrated on a 5GHz to 6GHz class AB power amplifier implemented in 180nm CMOS. Wideband cancellation of >48dB and >57dB at 20dBm and 10dBm Tx output power, respectively, is measured in CW. Cancellation of >30dB for an actual 160MHz 802.11ac OFDM packet around a carrier frequency of 5.2GHz together with EVM of -33dB is demonstrated. Measured Tx power added efficiency (PAE) for concurrent Tx-SIC operation is 35% and 6.4% at peak and RMS (10dB backoff) power, respectively. Rx loss is lower than 1.6dB at RMS Tx power within the signal frequency band.