| 摘要 |
PURPOSE:To obtain a crystal surface acoustic wave resonator with low equivalent resistance and low loss by adjusting arrangement of the interdigital transducer IDT pair number and number of reflectors and the referenced film thickness of the IDT electrodes. CONSTITUTION:In selecting number of pairs of the IDT electrodes 2 as N (N is an integral number being '1' or over) and the number of reflectors 3 as M (M is an integral number over '1'), the relation of N+M<=200 and N/MU>=1.4 is obtained and the film thickness H0/lambda which is the referenced film thickness H0 of the IDT electrode 2 with respect to the period lambda of the IDT electrode 2 is selected as 2.5%<=H0/lambda<=4.0%. The peak value of the resonance sharpness Q is decided by the effective pair number N'=N+M and the referenced film thickness H0/lambda of the IDT electrode 2. Since the Q is not so much changed depending on the arrangement of the IDT pair number N and the number M of the reflectors 3, the ratio of N to M(=N/M) is adjusted so as to decrease the equivalent resistance R1. Moreover, since the equivalent resistance R1 depends also on the referenced film thickness H0/lambda of the IDT electrode 2, the minimum value of the resistor R1 is selected by optimizing the N/M and the H0/lambda. Thus, the surface acoustic wave resonator in a small size and of low loss is obtained.
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