Periodic stepped-impedance resonator (PSIR) bandpass filters with multispurious suppression

Abstract

Periodic stepped-impedance resonators (PSIRs) are proposed to design bandpass filters for multi-spurious suppression. Denoted as PSIRN, a PSIR of lambda/2 long at design frequency f(0) consists of N periods of hi-Z and low-Z sections. A PSIRN coupled section shows transmission zeros at various frequencies. The zeros can be tuned by changing the impedance ratio of the hi-Z and low-Z sections, and can be adopted to suppress the spurious peaks. Responses of the PSIR filters show good rejection in the upper stopband.