| 摘要 |
PURPOSE: A surface acoustic filter is provided to improve the signal processing by controlling a shape of a plate for use in a capacitor and a distance to a metal case. CONSTITUTION: An IDT(InterDigital Transducer) metal electrode(4) for input is formed on a surface of a piezoelectric substrate(2) in the form of teeth. An IDT metal electrode(6) for output is separated from the IDT metal electrode(4) and formed in the form of teeth. A bonding pad(8) for an input signal is electrically connected to the IDT metal electrode(4). A bonding pad(10) for an output signal is electrically connected to the IDT metal electrode(6). A metal case(12) wraps an external side of the piezoelectric substrate(2). A plate(14) for a capacitor is formed on the IDT metal electrode(4) in order to improve the filter characteristics. |
