Ferroelectric thin film based tunable devices for software defined radio application

In this paper, we present a model of ferroelectric thin film based tunable device on silicon substrate for software defined radio (SDR) application. This model utilizes an interdigitated capacitor (IDC) structure and is showing high tunability besides being small in size. The IDC used in the filter is designed using Agilent ADS software and is simulated using planar and fullwave electromagnetic simulators. The modeling of the IDC on multilayer substrate is also discussed in this paper. An IDC structure as per this model is realized and characterized. Capacitances of 1 pF to 3.5 pF are obtained for 0.35 μm thick ferroelectric thin films on 500 μm silicon substrates over the frequency range of 1–4 GHz from realized IDC and 2 pF to 8 pF from the 3D electromagnetic simulation. Using the IDC structure realized, a tunable filter is designed, simulated and the results are discussed.