Contents I. Introduction
As the development of full-duplex wireless communication in recent years, self-interference cancelling technology has attracted much attention. Therefore, there is a great meaning that increasing isolation and improving transmission efficiency of transceiver for enhancing signal reception capability. The signal entering receiver contains desired received signal and own transmitted signal, and the own transmitted signal would cause self-interference. Various methods for cancelling SIC have been proposed [1]-[6], QHx220 chip is used for changing phase amplitude among three antennas in [1], the phase difference between the two transmitting antennas and the receiving antenna turns to 180 degrees achieving SIC. Balun structure is another structure often appear in SIC design, the inverted copy signal obtained by the balun is a template which could be adjusted. The adjusted signal is summed with the real self-interference signal at the receiving end [2]. The multi-tap self-interference cancellation structure utilize the different delays and gains of multi-tap to reconstruct self-interference channel for cancelling self-interference [3]-[4]. Specially, multiple non-uniform pre-weighted taps design is proposed to improve system isolation by cancelling both the direct antenna coupling as well as multipath effects which reconstructs a typical interference channel [4]. However, there is few discussions about the transmitting efficiency in self-interference cancellation circuits.
