Microstrip multistage coupled ring active bandpass filters with harmonic suppression

摘要

A novel microstrip active bandpass filter with harmonic suppression is investigated. The structure is composed of multiple coupled passive and active rings. A microstrip active bandpass filter at 1.37 GHz with a gain of 6 dB, return loss <15 dB and a harmonic suppression ratio over 25 dB has been implemented.