Differential Bandpass Filters Based on Dumbbell-Shaped Defected Ground Resonators

TL;DR

This paper introduces a novel dumbbell-shaped defected ground resonator for differential bandpass filters, demonstrating high common mode rejection and a systematic design approach validated by simulations.

Contribution

It presents a new dumbbell-shaped defected ground resonator and its application in designing higher order differential bandpass filters with improved rejection.

Findings

Achieved over 57 dB common mode rejection

Validated circuit model with electromagnetic simulations

Designed a third-order differential filter

Abstract

This letter presents a dumbbell-shaped defected ground resonator and its application in the design of differential filters. The operation principle of the dumbbell-shaped resonator (DSR) coupled to differential microstrip lines is studied through a circuit model analysis. The proposed circuit model is validated through the comparison with the electromagnetic simulation results. It is shown that the bandpass configuration of microstripline- coupled DSR can be used to design higher order bandpass filters. The design procedure is explained by developing a thirdorder filter prototype. The designed filter shows more than 57 dB common mode rejection within the differential passband.