| 摘要 |
PURPOSE:To cancel mismatching by using a conductive thin film wiring, which is provided on the piezo-electric characteristic substrate where an inter-digital transducer will be provided, as a micro strip line to form an impedance matching circuit. CONSTITUTION:For the purpose of obtaining the matching to an external circuit, a thin film distribution constant matching circuit is provided on the propagation path of the elastic surface unit where input inter-digital transducer 5 and output inter-digital transducer 6 are provided on piezo-electric substrate 3. The thin film distribution constant matching circuit consists of the micro strip line where piezo- electric substrate 3 is used as a dielectric and conductive thin film wirings 7 and 9 are provided, and selects properly a characteristic impedance to obtain the matching to the external circuit by changing the length and the width of conductive thin film wirings 7 and 9. Now, 11 in the figure indicates a shield electrode. |
