| 摘要 |
PROBLEM TO BE SOLVED: To provide a broadband piezoelectric filter which is capable of attaining broadbanding and securing great attenuation out of a passband and further which is inexpensive and easy to manufacture. SOLUTION: In a piezoelectric filter, two sets of energy confinement 2-pole filters formed with common ground electrodes facing divided strip-shaped input/output electrodes are formed on a principal surface of a piezoelectric substrate. First and second 2-pole filters are provided while being formed with input/output electrodes disposed proximately on one front side of each of piezoelectric substrates, and formed with ground electrodes on the counter rear side. The output electrode of the first 2-pole filter is connected to the input electrode of the second dipole filter, and a capacitor is provided while connecting its one end to that connecting point and grounding another end. In such a piezoelectric filter, in the 2-pole filters, each of the input/output electrodes are constituted of three approximately parallel strip electrodes, two strip electrodes on both sides are connected as input electrodes or output electrodes, and one central strip electrode is used as an output electrode or an input electrode. COPYRIGHT: (C)2006,JPO&NCIPI
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