Optimized design of a low-pass filter using defected ground structures

A novel three-pole low-pass filter is designed using low impedance microstrip line and one DGS section in this paper. An equivalent circuit model of a defected ground structure (DGS) is applied to study the characteristics of DGS. Parameters of the model are extracted from the EM simulation results by matching it to a one-pole low-pass filter. The lumped element values of the low-pass filter are optimized in circuit simulator by applying the circuit model of DGS. It is demonstrated that the filter can provide a sharp rate of attenuation in the stop-band as predicted. To further verify this method, a filter using DGS is fabricated measured. The comparison between simulation and measurement confirms the effectiveness of the proposed method.