Design and Analysis of Heterodyne Self-Interference RF Adaptive Cancellation Systems

With the extensive deployment of electronic information systems in modern RF integrated platforms, the issue of co-site, co-channel, or adjacent-channel interference has become increasingly severe. To address this problem effectively, the digitally controlled adaptive self-interference cancellation technology is considered as a viable solution. However, due to limitations in accuracy and the cost of high-speed analog-to-digital converters (ADCs), existing digitally controlled cancellation techniques face challenges when applied directly to the microwave band. In order to expand its working frequency range, mitigate the impact of ADC quantization noise, and accommodate diverse system configurations, three heterodyne self-interference cancellation structures are proposed and the working principle of the cancellation systems are derived in detail. Specially, the analytical expression between the cancellation performance and the system parameters is obtained, and the working boundary is also clarified. Simulation and experimental results demonstrate strong agreement with theoretical derivations, validating the effectiveness of the proposed structures.