Investigations of new materials, CTGS and CNGS, for SAW applications

摘要

Recently, SAW material parameters have been reported for CNGS, CTGS, SNGS and STGS. These materials are in the same family as LGS, LGN and LGT but have a lower density, differing coupling coefficients, higher velocity, and differing temperature coefficients. As compared with quartz, these materials have a higher density, lower velocity, higher electromechanical coupling coefficient, and higher temperature of operation without degradation of piezoelectric properties. Initial efforts have been made on investigating the various SAW parameters of CNGS and CTGS. Very little material is available, but very interesting properties have been found while investigating the Y-cut CNGS and CTGS substrates. It has been observed that there is a temperature compensated propagation angle near room temperature which is both promising in itself, as well as suggesting other compensated cuts may be possible at differing cut angles. Electromechanical coupling, velocity, temperature coefficient of frequency, power flow angle, and fractional frequency curvature results are provided and compared with those of quartz. In addition, a comparison of previously published results for CNGS, CTGS, SNGS, and STGS Y-cut substrates are given. These results include coupling coefficient, velocity, capacitance, and reflectivity measurements for various propagation angles. These results are also compared with previously reported measurement for LGT and LGN and a discussion is provided. Based on reflectivity measurements and parameter extraction, a COM model is used to predict SAW resonator performance and fabricated SAW resonator results are provided and compared with the COM model.