Exploration of design guidelines for cavity-backed dumbbell-shaped DGS common-mode filters

This paper presents a study on the design guidelines for the common-mode filters with cavity-backed dumbbell-shaped defected ground structures (CB-DB-DGSs). An equivalent circuit model was first developed to explain the physical insight of the CB-DB-DGS common-mode filter. With the help of the equivalent circuit model, the design parameters of the DGS and the frequency behavior of the filter are correlated. Typical ways to tune the equivalent capacitance and inductance are also explored. As a result, a design guideline towards a CB-DB-DGS filter with desirable frequency responses is developed.