Optimization of BST thin film phase shifters for beam steering applications

Barium Strontium Titante (BST) thin film based varactors are optimized for implementation in electrically controlled, analog phase shifters. Varactor tunability / phase shift is derived from ferroelectric BST being used as the dielectric layer in a parallel plate capacitive structure. The application of a low (0-8V DC) bias enables a decrease in varactor capacitance and creates a resulting phase shift. Optimization is performed though the simulation of varactor device variations including varied parallel-plate area and dielectric thickness. Parameters for phase shifter optimization include insertion loss, device size, and figure of merit (FOM) while requiring 360 degree phase shift from all designs. Though extensive simulations, a 6x6 æm² varactor based phase shifter with a dielectric thickness of 200 nm is determined to be optimal based on these criterion. A Monolithic Microwave Integrated Circuit (MMIC) and hybridized circuit are designed to demonstrate beam steering capabilities of the optimized phase shifters. Though fabrication of the varactor and phase shifter devices, experimental results are obtained to validate simulation performance and observations