Design and analysis of film bulk acoustic resonator (FBAR) filter for rf applications

Abstract

The RF band pass filters are important for wireless communication applications. They can be realized using Thin Film Bulk Acoustic Resonator (TFBAR).TFBAR is designed using Aluminium Nitride (AlN) and electrodes of piezoelectric material are made with Platinum (Pt).Various modelling techniques has been used for realizing three layered TFBAR structure. Modified Butter worth-van Dyke model (MBVD) is one used for numerical simulation of AlN film and thin electrodes. The result shows that Lm, Cm, Rm and Co model is perfectly applicable for predicting the response of TFBAR. The proposed design is realized by connecting three series and two shunt FBARs in ladder configuration. In the present work, the filter has been designed for a bandwidth of 270 MHz at -3 dB. The minimum insertion loss of -0.9 dB and return loss of -25 dB are obtained for VSWR ≤ 2 at resonance frequency. © 2012 Ramakoti Reddy and Chandra Mohan.