A design of group delay equalizer using series and parallel resonator

Abstract

A novel method of designing a group delay equalizer consisting of a typical 3-dB hybrid coupler combined with one of newly proposed 4 types of resonator is presented. It is designed by applying the phase obtained from the reflection coefficient between the 3-dB coupler and the proposed resonator to the group delay formula. Once the resonance frequency with the group delay as the peak is set to form a desired band by setting the parallel and series resonance frequencies, each component value of the proposed equalizer is obtained. In order to improve the group delay bandwidth, the proposed equalizers with different target frequencies are connected as cascaded. One of the proposed 4 types of equalizers was implemented using open and short stubs due to the fabrication limitation of lumped components, and its measurement results showed that the insertion loss is under -1 dB, and the group delay is 4.5 ns with +/- 1.5 fabrication error. This implies that the measurement results were well matched with the design method of the proposed equalizer.