| 摘要 |
PURPOSE:To control easily the resonance frequency of a surface acoustic wave device, by allowing an impedance converting circuit to vary impedance values when a power source and a load side are viewed from the surface acoustic wave device. CONSTITUTION:On a piezoelectric substrate 201, surface acoustic wave transducers 202 and 203 for energizing and reception are formed. Between the transducer 202 and power source impedance, the impedance converting circuit 20 consisting of a coil 204 and capacitors 205 and 206 is connected. On the other hand, the impedance converting circuit 30 consisting of a coil 207 and capacitors 208 and 209 is connected between the transducer 203 and load impedance 212. Those impedance converting circuits adjust the load impedance and power source impedance to adjust the resonance frequency of a surface acoustic wave easily. |
