Realization Of Transmission Zeros Research Articles

A systematic approach towards realization of transmission zeros in TE 01δ mode dielectric resonator filters with all iris couplings

This paper presents a novel method using a coupling matrix to realize dielectric resonator filters with Transmission Zeros (TZs). This method eliminates the necessity of capacitive coupling in conventional DR filter designs with TZs. Using the proposed technique, the cross-coupling sign can be changed systematically while the amplitude frequency response is kept unchanged. The method is independent of the filter physical structure and all design steps are based on coupling matrix equation and models. Therefore, unlike the extracted pole technique, this method not only does not require time consuming optimization in full wave simulations but also the extra resonator in this method helps in improving the group delay performance of the filter. After presenting the method, the calculated coupling matrix for a 7 × 4 DR filter will be realized using TE01δ mode of cylindrical dielectric resonators and simulation and measurement results will be compared.

Realization of transmission zeros in combline filters using an auxiliary inductively coupled ground plane

The out-band transmission zeros of the multilayer low-temperature co-fired ceramic bandpass filter are studied. The design target of this filter, with passband between 2.3-2.65 GHz (the true application is 2.4-2.483 GHz), is to reject the local oscillator and image signals and, in the mean time, to suppress the harmonic frequency. This filter is a modified three-pole combline filter, which can easily achieve a high rejection rate and low insertion loss. The source-load coupling capacitor incorporation with cross-coupling grounding inductors can generate three transmission zeros. By properly adjusting the inductance values of the inductors between three resonators and ground the transmission zero can easily be manipulated at a high-side skirt to suppress the harmonic frequency. The measured results match well with the electromagnetic simulation that provides evidence for the feasibility of the proposed design.

Realisation of transmission zeros with two RC parallel ladders

The polynomial decompositions due to Calahan and Horowitz can be effectively used for the synthesis of passive RC parallel ladders to realise any zeros of transmission including those on the positive real axis. Only two ladders are sufficient. One of the ladders will be connected via a voltage amplifier having a gain of ±1.