| 摘要 |
PROBLEM TO BE SOLVED: To shorten whole element length and to provide a small sized and satisfactory characteristic by forming transmission side and reception side interdigital electrodes (IDT) in different transmission paths, and transmitting the energy of a surface acoustic wave between the transmission paths by making it straddle the transmission paths in a mode connection-type reflector. SOLUTION: A surface acoustic wave obtained by applying the input voltage (Vin) of a signal source 118 to transmission side IDT1 105 and exciting it is transmitted to the direction of an X axis 119 orthogonal to electrode fingers 112, 115 and 114 and it is made incident OIL the reflector 1 101 of a mode connection-type reflector. It is transmitted to reflectors 2 102 and 3 103 in a mode connection phenomenon. It is reflected in the direction of -X, and is received by reception-side IDT2 106 and IDT8 107. Then an electric signal (Vout) between the terminals of a terminal impedance 117 is obtained. The frequency characteristic of the SAW filter is given by Vout/Vin. The multiple electrode finger groups of IDT and the reflectors are orthogonal to the phase travel direction of a surface acoustic wave and are periodically arranged in parallel.
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