Filter banks implemented with integrated thin film resonators

Filter banks composed of five or more bandpass filters fabricated on a single die have been demonstrated and are under continuing development. Such filters will find applications in multi-channel radios, spectrum analyzers, and in other frequency control applications. Fabrication of ladder bandpass filters requires that resonators be built at two or more frequencies for each filter. In the simplest form of the ladder filter, at least one frequency is needed for the series resonator and a lower frequency for the shunt resonator. This paper reports on a technique to fabricate multiple frequency resonators and experimental results for a simple five channel filter bank