NOVEL CAPACITIVE GAP-COUPLED BANDPASS FILTER USING NON-UNIFORM ARBITRARY IMAGE IMPEDANCE

Abstract

This paper introduces a new design technique for a capacitive gap-coupled bandpass fllter (BPF) using non-uniform arbitrary image impedances. Based on the proposed BPF equivalent circuit model, the fllter's design equations are derived, and they are validated from comparisons of the calculated and simulated results. For this theoretical veriflcation, the BPF using non-uniform arbitrary image impedances is designed using the speciflcations of: center frequency (fc) = 5:8GHz, fractional bandwidth (FBW) = 3:5%, and fllter stage (N) = 3. The calculated and simulated results of the designed fllter show good agreement. The BPF using the proposed design method could provide an advantage that one can arbitrarily determine two difierent image impedances, which ultimately afiects the BPF's coupling gaps and line widths. This could result in suitable fllter dimensions, i.e., gaps and line width, for a conventional low resolution photolithography fabrication although a low or high dielectric constant substrate is used for the design.