An Integrated CMOS Passive Self-Interference Mitigation Technique for FDD Radios

This paper presents an integrated passive self-interference mitigation (SIM) technique for FDD radios. A Four Port Canceller (FPC) serves a dual function as a receiver input matching network, and provides an auxiliary path from the transmitter (TX) to the receiver (RX) to perform leakage cancellation, with minimal penalty on the RX noise figure (NF), and power consumption. An example of this technique is applied to the design of a WCDMA front-end consisting of a low noise amplifier (LNA), the FPC, and an emulated power amplifier (PA) in a 40 nm, 6-metal-layer TSMC CMOS process. With proper tuning of the FPC and the use of an off-chip +30 dBm power amplifier, greater than 20 dB of TX leakage suppression is achieved over a cancellation bandwidth of 5 MHz.