Compact bandpass filter with wide stop band response based on meandered-line stepped-impedance resonator using IPD process

Abstract

This letter presents a compact size, wide-band bandpass filter (BPF) with high selectivity using integrated passive device technology. The structure of the proposed BPF consists of electromagnetically coupled stepped-impedance resonators (SIRs). To miniaturize the size of the proposed BPF, the size of the SIR was geometrically reduced significantly by meandering the line widthwise. Additionally, a uniform-impedance stub, which was placed between the SIRs to enhance the level of electromagnetic coupling between them, reduced the size of the BPF and also improved its pass band return loss. To verify the proposed method, a protocol BPF with central frequency of 6.72 GHz was designed, simulated, and fabricated on a Gallium Arsenide substrate. The measured return and insertion loss of 22.7 and 1.58 dB, respectively, indicated the high pass band selectivity of the BPF. Additionally, the presence of a transmission zero at 8 GHz with a measured suppression level of 37 dB in the stop band improved out-of-band selectivity of the BPF. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1466–1470, 2015