SURFACE ACOUSTIC WAVE DEVICE

• Main Author: EHATA YASUO
• Format: Patent
• Language: English
• Published: 16.05.1989
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS

PURPOSE:To make the band of a low loss filter wide by specifying a product of a surface acoustic wave reflecting quantity per electrode finger and the logarithm of the electrode finger constituting an interdigital converter. CONSTITUTION:Assuming surface acoustic wave reflecting quantity per one of electrode fingers 303 and 304 constituting an interdigital converter 3 as epsilon, and the logarithm of the interdigital converter 3 as N, then the interdigital converter 3 is constituted so as to satisfy epsilonN>=15. Thus, the reflection of the surface acoustic wave in electrode in the electrode fingers 303 and 304 constituting the interdigital electrode is actively used, two different electrodes of the electrode fingers 303 and 304 constituting the interdigital electrode are made into a pair, the logarithm is enlarged extremely, and thus, the impedance of the interdigital converter 3 can be extremely minimized over a wide frequency band. Thus, a low loss filter is obtained.