Patent ID: 6259336
Filing Date: 2001-07-10
Classification: H03H

Abstract:
A resonant surface acoustic wave filter device, comprising:a piezoelectric substrate;an inter-digital transducer that is formed on the piezoelectric substrate and has a first electrode area that excites a first surface acoustic wave and a second electrode area that excites a second surface acoustic wave of inverted phase with respect to the first surface acoustic wave; andgrating reflectors formed at both sides of the inter-digital transducer along a direction of propagation of the first and second surface acoustic waves that are excited by the inter-digital transducer,wherein a pitch of an electrode fingers array of the second electrode area of the inter-digital transducer is set approximately equal to a pitch of an electrode fingers array of the first electrode area to make frequency characteristics of a pass band of the filter device flat such that the second surface acoustic wave partially counteracts the first surface acoustic wave.