Patent ID: 7298231

Claim:
A surface acoustic wave device comprising: a piezoelectric substrate; a first filter element formed on one main surface of the piezoelectric substrate, and comprising first input/output electrodes, a first ground electrode, and a first IDT electrode; a second filter element formed on the same surface of the piezoelectric substrate, comprising second input/output electrodes, a second ground electrode, and a second IDT electrode, and having a different frequency band from the first filter element; and a circuit board for mounting the surface of the piezoelectric substrate, the first ground electrode and the second ground electrode being electrically separated from each other on the surface of the piezoelectric substrate, a first grounding conductor terminal connected to the first ground electrode and a second grounding conductor terminal connected to the second ground electrode being separated from each other on a surface, on which the piezoelectric substrate is mounted, of the circuit board, a third ground electrode being provided on a surface on the side opposite to the surface, on which the piezoelectric substrate is mounted, of the circuit board or any inner layer surface of the circuit board, and first and second via conductors respectively connected to the first grounding conductor terminal and the second grounding conductor terminal and penetrating the circuit board down to the position of the third ground electrode, wherein the first ground electrode is formed in a single electrode on the one main surface of the piezoelectric substrate, and the second ground electrode is formed in a single electrode on the one main surface of the piezoelectric substrate, and wherein the first IDT electrode comprises a series IDT electrode connected between the first input/output electrodes and parallel IDT electrodes connected between a signal line and the first ground electrode, and the second IDT electrode comprises a series IDT electrode connected between the second input/output electrodes, and parallel IDT electrodes connected between the signal line and the second ground electrode.