Accurate computer aided design of interdigital filters applying a coupling identification method

Interdigital filters are found to be difficult to adjust because of improper couplings that occur at high frequency. To solve this problem, a new optimization method for the design of high frequency interdigital filters is presented in this paper. This optimization method uses an accurate computer aided design method, based on the identification of each resonator coupling including parasitic ones. In order to show the feasibility of such a method an example of a 3.1 GHz band-pass filter around 18.95 GHz is studied.