Kazuhiko Morozumi

Ceramic Resonators Using BGS Waves

The BGS wave has generally a large electromechanical coupling factor and a characteristic of complete reflection at stress-free edges of substrates. Therefore, a broad-band super-miniature resonator with a small capacitance ratio can be made utilizing the free-edge reflection property of a BGS wave. A BGS wave resonator using PZT was developed for use as a resonator for an additional trap at fas (adjacent sound carrier frequency) in VIF circuits of TV sets and VCRs. Testing as a trap device in VIF showed that this device has better properties than LC trap circuits.

Characteristics of Bleustein-Gulyaev-Shimizu Wave Resonators on Ceramics at High Frequencies

At frequencies above 60 MHz , tuning-free surface acoustic wave (SAW) resonators with many reflectors using Rayleigh SAW are generally used. However, Rayleigh SAW resonators for use in the 60–150 MHz range have some disadvantages such as cost. We have already developed a BGS wave resonator, which is being used commercially in the 30–60 MHz range. When we improved the characteristics of BGS wave resonators by using small-particle , poreless ceramic substrates developed for high-frequency BGS waves, we obtained good resonance characteristics up to 160 MHz. We also obtained good characteristics when we tested the resonator in a DECT demodulator circuit.

Characteristics of BGS wave resonators using ceramic substrates and their applications

We tackled the challenge of developing the commercially usable Bleustein-Gulyaev-Skimizu (BGS) wave resonators using piezoelectric ceramic substrates in the frequency range between 30 and 110 MHz. We developed two types of resonators (low Q type and high Q type). The low Q type BGS wave resonators have been evaluated as resonators for an additional trap and for an auto frequency tuning (AFT) in a video intermediate frequency (VIF) circuit of TV and VCRs, and as resonators for digital European cordless telephone (DECT) demodulator. The high Q type BGS wave resonators have been evaluated as resonators (75 MHz) for personal computer clocks. In these applications the BGS wave resonators exhibit excellent characteristics.