Patent ID: 7456705

Claim:
A SAW device formed on a main surface or main surfaces of one or a plurality of piezoelectric substrates, comprising: a ladder-type transmission SAW device comprising one or a plurality of transmission SAW resonators connected in series with a transmission signal line and one or a plurality of SAW resonators for transmission connected in parallel with the transmission signal line; and a ladder-line receiving SAW device comprising one or a plurality of SAW resonators for receiving connected in series with a receiving signal line and one or a plurality of receiving SAW resonators connected in parallel with the receiving signal line, wherein the ratio (LT/PT) of the width LT of electrode fingers in an IDT electrode in at least one of the transmission SAW resonators to the pitch PT between the adjacent electrode fingers in the IDT electrode, and the ratio (LR/PR) of the width LR of electrode fingers in an IDT electrode in at least one of the SAW resonators for receiving to the pitch PR between the adjacent electrode fingers in the IDT electrode satisfy the following expression: ( LT/PT )<( LR/PR ) and the respective pitches between the electrode fingers in the transmission SAW resonator connected in series with the transmission signal line and the receiving SAW resonator connected in parallel with the receiving signal line are substantially identical.