A Wideband 90° Differential Phase Shifter with Circular Open-Circuited Stubs

It remains ongoing challenges in the design of printed wideband phase shifters, owing to strict requirements for the bandwidth, insertion loss, phase deviation and size in a variety of applications. In this paper, a wideband 90° differential phase shifter with circular open-circuited stubs is proposed. The transmission line model is used to analyze the circuits, and the full-wave simulation and parametric optimization are performed by CST in combination of Genetic Algorithm MATLAB routines. A phase shifter prototype is manufactured and validated by measurements, which exhibits an operating bandwidth of 90.1% from 2.5 GHz to 6.6 GHz for insertion loss <; 0.6 dB, return loss > 13 dB and a phase deviation of ±7°.