Balanced Nonreciprocal Bandpass Filter Based on Time‐Modulated Resonators With Linear‐Phase Characteristics

ABSTRACT In this paper, a balanced nonreciprocal linear‐phase bandpass filter (BPF) based on time‐modulated resonators is reported for the first time. A linear‐phase response is achieved by integrating group delay equalization circuits adjacent to both the balanced input and output ports of a balanced nonreciprocal BPF, implemented on a microstrip circuit. Compared to conventional passive BPFs, the balanced nonreciprocal BPFs based on time‐modulated resonators exhibits different group delay characteristics. This work introduces an innovative group delay equalization circuit, specifically designed for nonreciprocal BPFs based on time‐modulated resonators. By utilizing resonators with different resonant frequencies under common‐mode and differential‐mode excitation, the balanced circuit provides effective common‐mode suppression, which enhances immunity to electromagnetic interference and crosstalk compared to single‐ended circuits. A microstrip prototype was fabricated for the proof‐of‐concept demonstration, and the measurements show good agreement with simulations.