Method of tuning thin film resonator filters by removing or adding piezoelectric material

摘要

The present invention provides a method for tuning a thin film resonator (TFR) filter comprising a plurality of TFR components formed on a substrate. Each of the TFR components has a set of resonant frequencies that depend on material parameters and construction. TFR bandpass filter response for example can be produced by shifting the set of resonant frequencies in at least one of the series branch TFR components so as to establish the desired shape of the bandpass response and the desired performance of the filter. The shifting may be advantageously performed by removing piezoelectric material from the series branch TFR component, providing a TFR filter with bandwidth and attenuation advantages over that conventionally achieved by down-shifting resonant frequency sets of the shunt TFR components by adding metal material. Additionally, the above method can be used to produce a stopband TFR filter with a desired response by removing piezoelectric material from the shunt branch TFR component, to up-shift the shunt TFR components' set of resonant frequencies with respect to the series branch TFR components.