Wideband and Electronically Tunable Microwave Phase Shifter Using Varactors with Relative Phase Shifts up to 360°

Journal article, 2021

In this work we present a new design of a Wideband Reflection-Type Tunable Phase Shifter (WRTTPS) for smart front-ends applications. The proposed WRTTPS is based on a short-circuited 3- dB/90° Branch-Line Coupler (BLC), whose characteristics can be electronically tuned using Variable Capacitance Diodes (VCDs) at the reflecting load. The combination of a transmission line in series with two parallel varactors enhances the phase shifter performance, and by adding twocrossed microstrip transmission lines to the conventional BLC the bandwidth improves from 17 to 43.34 %. We experimentally implemented the phase shifter and demonstrated that it produces a wide tunable phase range and full transmission within the experimental uncertainty. This novel topology has a fractional bandwidth of around 43.34 % which is greater than 1 GHz at the central frequency 2.63 GHz and provides a relative phase shifting up to 360°. A good agreement has been shown between simulated and measured results.