Piezoelectric resonator and piezoelectric filter using the same

• Main Authors: TAKEUCHI MASAKI, TSUKAI NORIMITSU, SHIBATA AKIHIKO
• Format: Patent
• Language: English; Korean
• Published: 09.01.2002
• Edition: 7
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS

PURPOSE: A piezoelectric resonator and piezoelectric filter utilizing the same are provided to have a small impedance that is less affected of spurious vibration, and a piezoelectric filter is provided to have a wide pass band that has a small ripple component in the pass band caused by the effect of the spurious vibration of the piezoelectric resonator. CONSTITUTION: A piezoelectric resonator(10) includes a substrate made of Pyrex glass or a material such as a quartz and a vibration section(20), formed on the substrate, provided with a dielectric thin film(14), a couple of electrode thin films(16) and a piezoelectric thin film(18). The electrode thin films(16) are formed at each sides of the piezoelectric thin film(18), and partially disposed through the piezoelectric thin film(18) to thereby form the pair of opposite electrodes(16). The piezoelectric resonator(10) further includes a supporting member for supporting the vibration section(20) which vibrates in an n-th mode of thickness longitudinal vibration or a thickness share vibration applied to the piezoelectric resonator(10). Each of the opposite electrodes(16) has a radius r and the vibration section(20) has a thickness t, wherein the r meet the requirements of r >= 20 t/n. 두께 세로 진동(thickness longitudinal vibration) 또는 두께 전단 진동(thickness-shear vibration)의 n차 모드를 사용하는 압전 공진기는, 압전층을 갖는 진동부, 한 쌍의 전극, 진동부을 지지하는 지지부를 포함한다. 한 쌍의 전극부는 유전층의 반대면에 각각 형성되고, 유전층을 경유하여 각각 부분적으로 겹쳐져서 대향전극부를 이룬다. 지지부는 두께 세로 진동 또는 두께 전단 진동의 n차 모드에서 진동부이 진동하는 것을 지지한다. 대향전극부는 반경 r을 갖는 실질적인 원형이거나 대체로 원형에 외접하는 다각형이 바람직하다. 반경 r은 부등식 20t/n ≤r 을 만족하는데, 여기서 t는 진동부의 두께이다.