90° Broadband asymmetrical open-short-stub phase shifter with inductance compensation

A 90° broadband asymmetrical open-short-stub phase shifter (PS) using inductance compensation is demonstrated. A typical stub-load PS uses the same characteristic impedances of the stubs. In this paper, the asymmetrical open-short stubs are proposed to improve the fractional bandwidth (FBW). Furthermore, the inductance of the via of the short stub is deliberately adopted to compensate the asymmetrical impedance. Measurement shows a FBW of 90.4 % for a phase difference of 90° ± 5° while Su is below −10 dB. The proposed phase shifter is fabricated on a low-cost 1 mm-FR4 substrate.

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