| 摘要 |
PURPOSE:To simplify the circuit by using an adhesive to stick two 3-terminal piezoelectric vibrating elements thereby making the pass band center of the amplitude characteristic coincident with a point of phase angle 90 deg. of the phase shift characteristic and using said piezoelectric resonator for the phase shift circuit of an FM demodulation circuit. CONSTITUTION:The piezoelectric resonator 1 is constituted by using an adhesives 3 so as to stick two 3-terminal piezoelectric vibrating elements 2, 3 formed symmetrically to the right/left. The elements 2, 2 are the piezoelectric vibration elements of the energy confinement type and thickness vibration mode in which split electrodes 5, 5 are formed to one side of the base 4 and a common electrode 6 is formed to the ground side. In the sticking above, the common electrodes 6 are overlapped and the split lead-out electrodes 7, 7' are directed upward for the one base 4 and directed downward at the other base 4. The electrodes 8 of the two bases are connected and led out and one set of electrodes in the opposite two-sets of split electrodes 7, 7' are connected so as to be crossed via the base and the split electrodes of the other set are led out to form IN, OUT, GND terminals respectively. Thus, in the resonator 1, the pass band center of the amplitude characteristic and the frequency at a point of phase angle 90 deg. of the phase shift characteristic are made coincident. The resonator 1 is used for the phase shift circuit of the qudrature type FM detection circuit, then a conventional RLC circuit is not required.
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