Thin Film Ferroelectric Tunable Devices for Reconfigurable Radios

In this paper, a summary of our work in the area of tunable microwave circuits based on thin film ferroelectrics is presented. First, a technique is introduced to improve the linearity of thin film ferroelectric tunable capacitors. Measurements show an improvement in the 3rd order intermodulation point at the input (IIP3) of 16 dB. Next, the design and fabrication of an impedance tuner employing thin film ferroelectric capacitors for applications in adaptive matching networks is described. An impedance tuning ratio of 4:1 was achieved. Lastly, the fabrication of a switchable thin film bulk wave acoustic resonator (FBAR) and its application in the design of switchable filters are discussed. The resonator is measured to have a series resonance of 1.975 GHz with a Q factor of 233 and a parallel resonance of 2.035 GHz with a Q factor of 218. The resonator is proposed to construct a switchable bandpass filter.