Longitudinal double mode surface acoustic wave filter

Abstract

Abstract PURPOSE:To obtain a pass band tat is free from the undesired spurious despite the use of an LiTaO3 piezoelectric substrate of 36 deg. Y rotation cut/X direction transmission by providing a coupling capacity at the connection part between sections of an energy shut-up type resonator in parallel to an interdigital filter in terms of electricity. CONSTITUTION:A 2-section energy shut-up type resonator is formed on an LiTaO3 piezoelectric substrate 21 of 36 deg. Y rotation cut/X direction transmission. A coupling capacity 30 is provided in parallel to a connection part between an output side tandem line electrode 23 of a 1st section and an input side interdigital electrode 26 of a 2nd section in terms of electricity. The capacity 30 consists of the interdigital electrodes set at such positions where they have no interference to the surface waves excited by the tandem line electrodes 22, 23, 26, and 27. Thus it is possible to obtain a longitudinal double mode surface acoustic wave filter which applies the substrate 21 and can approximate the undesired spurious to the resonance point of a longitudinal zero-order mode.

Inventors

• 👤 Yutaka Tada
• 👤 裕 多田

Bibliographic Details