Wideband Self Interference Cancellation (SIC) RF Front End for Simultaneous Transmit and Receive (STAR) Radios

Abstract

<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> Simultaneous transmit and receive (STAR) radio architectures are of strong interest as they can double data rates in communication links. To achieve acceptable performance, high power coupled from the transmitter into the receiver must be suppressed at the receiver end. In this regard, a wideband RF front end is required, which will provide high isolation. In addition to the antenna, this designed RF front end board includes a custom-designed RF-SIC filter, multiple power splitters/combiners and baluns to generate a weighted coupled signal at the receiver. This captured signal from the transmitter is used to cancel out the interference from the overall receiver chain. Combining this RF-SIC board with a custom-designed ring monopole antenna makes it possible to achieve >70dB of isolation at the RF front end across the entire 2-3GHz band. This high isolation between the nearby transmitter and receiver ensures wideband STAR operation. This paper describes the design approach and the associated fabrication challenges of the RF-SIC board.