Patent ID: 6731187
Filing Date: 2004-05-04
Classification: H03H

Abstract:
A dual mode filter comprising:a casing substrate having an input electrode, an output electrode, two ground electrodes, and a relay electrode provided thereon; first and second filter elements mounted on the casing substrate; and a cap connected and fixed on the casing substrate so as to cover the first and second filter elements; wherein each of the first and second filter elements includes a first terminal electrode provided at a first end of a first principal surface of a piezoelectric substrate, a second terminal electrode provided in a central portion of the piezoelectric substrate, a pair of segmented electrodes provided in a portion between the first and second terminal electrodes and which are connected to the first and second terminal electrodes, respectively, a counter electrode provided on a second principal surface of the piezoelectric substrate and which is opposed to the segmented electrodes, so as to define a dual mode vibrator, and a third terminal electrode provided at a second end of the piezoelectric substrate and which is connected to the counter electrode; the first terminal electrode of the first filter element being connected to the input electrode on the casing substrate via a conductive bonding material, and the third terminal electrode being connected to one of the two ground electrodes on the casing substrate via a conductive bonding material; the first terminal electrode of the second filter element being connected to the output electrode on the casing substrate via a conductive bonding material, and the third terminal electrode being connected to the other of the two ground electrodes on the casing substrate via a conductive bonding material; and the second terminal electrode of the first filter element being connected to the relay electrode on the casing substrate via a conductive bonding material, and the second terminal electrode of the second filter element being connected to the relay electrode on the casing substrate via a conductive bonding material.