X -Band Reflection-Type Phase Shifters Using Coupled-Line Couplers on Single-Layer RF PCB

• Published in: IEEE microwave and wireless components letters 2018-09, Vol.28 (9), p.807-809
• Main Authors: Venter, Johannes J. P., Stander, Tinus, Ferrari, Philippe
• Format: Article
• Language: English
• Subjects: <italic xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">X -band; Bandwidth; Couplers; Couplings; Insertion loss; Phase shifters; Radio frequency; reflection-type phase shifter (RTPS); Varactors
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2018.2853562

In this letter, an X-band reflection-type phase shifter is presented. It is based on a single-layer stub-loaded coupled-line coupler loaded by two-varactor tuning circuits. This choice of coupler significantly improves on the phase shifter bandwidth achievable with a branch-line coupler, as it features a lower phase imbalance across the band of interest. The proof-of-concept prototype achieves better than 10-dB return loss across a 20% fractional bandwidth. The phase shifter further exhibits insertion loss of 2.1 ± 1.3 dB and maximum phase shift of 392° at 10 GHz, leading to a state-of-the-art figure of merit at X-band of 115°/dB. The occupied area is 0.25\lambda _{g}^{2} .