Isolation Enhancement Based on Adaptive Leakage Cancellation

In the design of direct-conversion architecture, an important issue is the leakage from the transmitter to the receiver, which can cause DC-offset problem. In this paper, an adaptive leakage cancellation method is proposed to improve the isolation performance. The fundamental concept of this method is to introduce an anti-phase signal, to cancel the leakage. In order to improve the performance, variable attenuator and phase-shifter are used in the system, and a closed-loop configuration is also employed. Both of the mathematical analysis and simulation about this method have been provided in this paper. And the results show that, good isolation performance can be achieved automatically and real-timely in this method.