A Straightforward Equivalent Circuit Approach for Characteristic Evaluation of Capacitor-Based Loaded-Line Phase Shifter

In this paper, characteristic evaluation of a reconfigurable capacitor-based loaded-line phase shifter is presented by utilizing an equivalent circuit approach. For this purpose, a straightforward equivalent circuit of the phase shifter composed of three microstrip lines and four loading capacitors is developed. The values of lumped elements for the equivalent circuit are determined from the physical dimensions of the phase shifter structure. By using the developed equivalent circuit, phase shifter characteristics, including reflection and transmission coefficients, are evaluated for a varied 0.2 pF to 1 pF capacitance range. The characteristics obtained from the proposed approach agree with the measured results.