A Microwave Interference Cancellation System Based on Down-conversion Adaptive Control

In the circuit design of interference cancellation systems based on Least Mean Square (LMS) algorithm, a mixer is required to realize the correlation calculation between the error signal and the reference signal. However, the DC offset of the mixer is hard to correct. Therefore, we propose a microwave interference cancellation system based on downconversion adaptive control (MICS-DCAD) of which the principle is to down-convert the microwave signals (both the error signal and the reference signal) to ultrashort wave band and use Gilbert multiplier for calculating the correlation. The null shift of the Gilbert multiplier is mainly temperature dependent, which facilitates accurate compensation and avoids the problem of DC offset suppression. We present a mathematical model to analyze the performance of MICS-DCAD. Experimental results are also provided to verify theoretical model as well as the feasibility of the proposed method.