Analysis and Optimal Design of Radio-Frequency Interference Adaptive Cancellation System With Delay Mismatch

Aimed at radio-frequency (RF) interference suppression, this article presents an RF interference adaptive cancellation system (RFIACS) with the down-conversion correlator and proposes the time domain model of the RFIACS with integrated delay mismatch about mixers, RF circuit, and intermediate frequency (IF) circuit. Then, the influence of the integrated delay mismatch and loop gain on the system stability, convergence time, and interference cancellation ratio is analyzed based on the time model. Studies show that the RF and IF delay mismatch each must be matched on their respective frequency bands and the proper arrangement of circuits and loop gain can effectively improve the cancellation performance of the system. Results of simulations and experiments with different parameters show that the theoretical model is valid and accurate. The research result is of much value to the circuit design and delay-matching debugging of the RFIACS.