A Novel Approach to Integrate Multiple Frequencies of Film Bulk Acoustic Resonators (FBAR) In A Single Chip
Z. Huang, Z. Suo, L.-P. Wang, D. Shim and Q. Ma
Intel Corporation, US
resonator, piezoelectric, FBAR, integration, tuning, reconfigurable radio, wireless communication
Driven by fast growth of wireless communications, film bulk acoustic resonators (FBAR) have been extensively studied as RF filters. Recently, an integrated RF solution, which could include multiple mobile bands, WLAN, Bluetooth, GPS, and etc., has drawn big research efforts to provide a multifunctional, cheap, and low-power radio. In 2004, G.Piazza et al. explored AlN piezoelectric resonators operating at contour modes to have multiple frequencies in a chip. However, a much lower electromechanical coupling coefficient (kt2) limits it for applications. In this paper, a novel approach was studied to achieve multiple resonance frequencies with high resonator performance. A tuning layer was added and patterned on a conventional FBAR. FEM was utilized to simulate the frequency response. The results showed that resonance frequencies can be modulated by varying pattern sizes of the tuning layer under the condition of pattern period smaller than the films thickness. Effective k332 were all maintained within 87% compared to the un-tuned one. This novel approach would lead to a viable solution of future integrated RF front end to realize the grand vision of the multiple-mode radio. More excitingly, the approach could be applied in different nano-/ micro-systems with integrated spectrum sensing capabilities.
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Nanotech 2005 Conference Program Abstract