State of the art SAW resonators in France

During the last three years Thomson has concentrated on producing reliable, low-noise, and high-stability SAW (surface acoustic wave) resonators. A complete resonator analysis was required, one which modeled effects such as transverse modes and intratransducer coupling. Research has yielded typically less than 1 p.p.m./yr aging and unloaded Q-factors higher than 18000 with resonators close to 500 MHz. The first oscillators realized at 320 MHz show a good phase noise spectrum. Standard production techniques coupled with a newly developed multichip all-quartz packaging technique were used in the resonator manufacture. In addition, with use of a finite element analysis, the mechanical structure of the resonator can now be optimized to minimize the accelerometric sensitivity, which is required in military environments. Details on the design, manufacture, and performance of resonators in the 300- and 500-MHz ranges are presented