A 10–50 GHz Ultrawideband Low Loss mmWave VO₂ Based Phase Shifter for Passive Scanning Arrays

This paper presents the design, fabrication, and characterization of a 10–50 GHz true time delay (TTD) 5-bit phase shifter based on single pole single throw (SPST) vanadium dioxide (V02) switches. The V02 switches are low loss, with less than 0.7 dB of insertion loss up to 50 GHz. Integrated inductors are utilized to realize a broadband impedance match. The phase shifter has a measured return loss of better than 10 dB, and a time delay resolution of 0.6 ps. The time delay variation is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$&lt; 1$</tex> ps over the 10 - 50 GHz band. The maximum insertion loss is 2.4 dB per bit at 40 GHz. The fabricated device has a size of 2.89 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{mm}^{2}$</tex>, which is 21°/0 of the inter-element lattice area, of a typical 40 GHz array.