Comparison of RF Cancellation approaches for UWB STAR Radios

To double spectrum efficiency, a well-known approach is that of using Simultaneous Transmit and Receive (STAR) radios. The goal is to suppress the coupling from the transmitter to the receiver, by using the knowledge of the transmitted signal. Successful implementation of STAR requires self-interference cancellation of at least 100 dB across the entire band. Antenna Tx/Rx signal isolation must be very strong to ensure no saturation occurs in the LNA and other components in the Rx chain. In this paper, we present to compare approaches to achieve improved isolation for single and multi-antenna radios across wide bandwidths. Measurements show that a combined 2 stage isolation of > 65 dB can be achieved.