A high performance C-band FBAR filter

In this paper a RF band pass filter in C-band based on film bulk acoustic resonator (FBAR) technology is developed. The measured insertion loss is less than 2.0 dB at the center frequency (5.2GHz) of the filter, and the signal attenuation near the pass band of the filter is greater than 50 dB. The measurement data are in good agreement with the design employing three dimensional electromagnetic simulation techniques. A method to move the transmission zeros of the FBAR filter is proposed by adding a capacitor element between the two shunt branches of the filter. Using the technique, an FBAR filter chip can be configured to meet different rejection specifications potentially.