Low‐loss W‐band CPW bandpass filter using annular CPW branch‐line coupler with open load stubs

Abstract

A W‐band coplanar waveguide (CPW) low‐loss annular branch‐line bandpass filter for planar integrated millimeter‐wave circuits is presented. It is designed by using the annular branch‐line coupler as a transversal filtering section by loading the coupled ports of the coupler with suitable open load stubs and taking the isolated port as the output node. The proposed W‐band bandpass filter shows very good performance, insertion‐loss of 0.7 dB with a 14.9% of 3 dB relative bandwidth at center frequency of 94 GHz and return loss is better than −27 dB at the center frequency. The designed and fabricated bandpass filter exhibits the good performance for monolithic integrated millimeter‐wave circuit applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2400–2403, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26264