Transceiver Architectures for Full Duplex Systems with Unmatched Receiver

In this paper, we present an overview of both the challenges and the state-of-the-art in full duplex (FD) integrated transceivers in terms of loss and noise. New circuit concept is presented for mismatched receiver design with a cancelling path. An implementation of LNA in 28nm CMOS process based on quadrature balanced (QB) structure achieves less than 0.5dB NF degradation and a 1dB TX insertion loss at 60GHz. This structure has a 10dB isolation from TX to LNA and can operate well for mm-wave frequencies where TX power is typically lower than 0dBm. With the QB receiver design the antenna is still matched.