Integration of microwave phase shifter with BST varactor onto TiO 2 /Si wafer

A BST ferroelectric thin-film microwave phase shifter with interdigital capacitors on TiO2/Si substrate is presented. The interdigital capacitors have 230 µm signal width, 100 µm signal to ground gap, and 10 µm finger gap. The device, with phase shifts of 142° and FoM of 107.3°/dB applied voltage of 50 V at 16 GHz, has been realised. The TiO2 buffer layer grown by ALD enables successful integration of BST-based microwave tunable devices with Si wafer.