Design and Implementation of an Analog High Power Broadband Self Interference Canceller for In Band Full Duplex

Abstract

A Self-Interference Canceler is the principle component that allows for Simultaneous Transmit And Receive (STAR) of radio signal broadcasting. Previous research and designs by other groups have resulted in systems that either operate at high powers or are capable of cancellation over a wide bandwidth. This work seeks to build upon previous research in order to design an analog SIC that is capable of both high power (∼100W) and wide instantaneous bandwidth (∼1GHz) cancellation. The system is designed as a vector modulator using off-the-shelf hybrid couplers and switches with a custom variable attenuator designed using PIN diodes in a Waugh attenuator architecture. The system was fabricated on a four layer PCB and measured with a network analyzer. Simulated results for variable attenuator and overall vector modulator are presented.