Switch-Based Non-Reciprocal Filter for High-Power Applications

This paper presents the first switch-based non-reciprocal filter. Compared to varactor-based ones, such designs are more robust against input power, and simpler to bias. Furthermore, the switches, implemented with PIN diodes, consume less power compared to transistor-based non-reciprocal filters. These switches connect extra capacitances to the resonators of the filter, such that switching them ON and OFF creates the necessary time-varying response to achieve non-reciprocity. The concept is designed and implemented on a third-order bandpass filter centered at 1.3 GHz. The measured isolation is 20 dB. The filter is also measured up to 4 W of input power with minimal degradation in performance, while consuming only 15 mW.