Broadband phase shifters using complementary frequency-dependent Δphase of low-/high-pass filters

Abstract

This letter presents a simple and compact design approach for broadband analog phase shifters and its demonstration. An octave bandwidth can be obtained by alternately cascading low-pass filters (LPF) and high-pass filters (HPF) that importantly provide complementary phase-changing characteristics over “frequencies.” Achievable phase change per segment can be multiplied by cascading multiple segments that operate as independent phase shifters, thereby reaching 360 degrees of phase shift. We demonstrate one- and two-segment phase shifters consisting of cascaded LPF-HPF-LPF structures, of which capacitors in each filter are implemented by varactors, over a frequency range from 0.7 GHz to 1.4 GHz. Measurements show 65.8 degree average phase shifts from the single-segment and 128 degree from the double-segment, which is about twice as much as the single-segment shifter's. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:664–666, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27345