Research On FBAR Modeling And Some Applications

With the rapid development of wireless communication technology, the radio frequency terminals are becoming more miniaturized and integrated. Compared with the conventional di-electric filter and SAW filter, thin film bulk acoustic resonator (FBAR) has high operating fre-quency, low insertion loss, high outband rejection, good temperature coefficient, high Q, small size, and compatible process with CMOS technology. Thus, this technology has widely applica-tion prospects.Three parts are researched in this paper, including the modeling and fabrication of FBAR, design of FBAR filter, and design of FBAR sensor signal processing chip. The main achieve-ments are listed as follows:1. Based on FBAR Mason model, the ADS simulation library is built up. And the HFSS three-dimensional electromagnetic field simulation model is also applied to achieve acous-tic-electromagnetic field co-simulation based on equivalent complex dielectric constant. The simulation results of these two models further verify the accuracy and reliability of the models. Based on the established model, different structures of longitudinal and shear mode FBAR are designed and fabricated, and the samples are tested. Test results show that FBAR has a Q factor about 1350.2. Designed the FBAR bandpass filters for GSM, PHS, and WCDMA terminal, respectively. And a multiplexer for MIMO terminal is also designed. Simulation results show that the filters and multiplexer have excellent filter characteristics which can meet the requirements of current communication terminals. Then we research the theory and design method of FBAR stacked filter, stopband filter, shear mode FBAR filter, and the corresponding filter design example is given. Moreover, a method for multipled coupled resonator filters with an isolation layer is proposed. We also analysis some FBAR filter parameters, including the parasitic parameters, bandwidth, out-band rejection, power capacity and temperature com-pensation. What's more, some new methods are proposed to improve the power capacity of FBAR or FBAR filter.3. Completed the design, tape out and test of FBAR sensor signal processing chip. Test results show that the function of sensor signal acquisition is normal except±1KHz frequency error. According to problems in the test, we improve the design of the chip. Thereby, the errors that exist in the counting process are eliminated effectively. And the improved chip is man-ufacturing again in SMIC 0.18μm process.