Until last years, filters for mobile operated in the 70-350 MHz frequency range with a quality factor times frequency (Q×f) product reaching values of around 9×10n12. The aim is now to reach a Qxf of 10n13. Progress on quartz material is a key factor success. We worked on the synthesis of quartz to get higher purity and larger size (100mm-4inches) to exceed characterization standard values (IEC 60 758 and JIS C 6704). Our Pure Premium Quartz (PPQ) AT wafers were compatible with fabrication of SAW devices. Multiple resonance resonators were manufactured. Two interdigitated transducers (IDTs) operating out of the Bragg conditions have been used. The device measurements have been compared with theoretical prediction, yielding an excellent agreement between both curves. Same for the Temperature Coefficient of Frequency (TCF). Further analysis identified an attenuation constant of 1 mdB/λ providing the measured Q factors and therefore a Q×f product of 8.96×10n12. Works in progress on quartz material should reach a Q×f product of 10n13 value on 150mm (6) AT wafers.
