In this paper, parallel plate varactor based phase shifter circuits using Barium Strontium Titanate (BST) thin films are presented. A cascade of 10, 15 and 20 parallel plate varactors were able to produce (150°, 258°, 297°), (218°, 381°,443°) and (227°, 402°, 464°) phase shift at (5, 10, 12 GHz) respectively. The 360° phase shift is achieved with small device size, low bias voltages (0-8 V), low leakage currents, low insertion loss and high figure of merit (FOM). FOM of 40, 33, 24 Degrees/dB is achieved with 10, 15 and 20 shunt varactors at 12 GHz respectively. The proposed circuit is very easy to fabricate which uses a CPW transmission line configuration and can be easily integrated with other circuits on chip.