Insertion Loss in Reflection-Type Microwave Phase Shifter Based on Ferroelectric Tunable Capacitor

A tunable capacitor based on a ferroelectric thin film grown on a dielectric substrate is a promising component for reconfigurable and tunable devices for numerous RF and microwave applications such as phase shifters, tunable filters, and tunable matching networks. The goal of this paper is characterization of the insertion loss in a reflection-type microwave phase shifter based on the ferroelectric tunable capacitor. The reflection-type phase shifter based on ferroelectric planar tunable capacitor was designed, manufactured, and tested. Its simulated and measured insertion loss and phase shift are compared. Two loss mechanisms in the phase shifter were distinguished: the loss in the tunable capacitor and the loss in the associated circuitry (metallization and substrate). The properly organized investigations of the dissipation of energy in metallization and dielectric substrate can result in a sufficient improvement of the quality of the devices. As a final result, one may anticipate that the figure-of-merit of a ferroelectric tunable or switchable phase shifter can reach 200 deg/dB