FM demodulation circuit

Abstract

Abstract PURPOSE:To make a tuning circuit into non-adjustment, and to reduce the number of out-fitted parts at the time of assemblihg it as an IC, by constituting in parallel a bridge circuit by connecting a first circuit connecting a solid-state vibrator to a resistor in series, to a second circuit connecting a capacitor to the resistor in series. CONSTITUTION:The first circuit in which a ceramics resonator X, and a resistor R1 are connected in series, and the second circuit in which a capacitor C1, and a resistor R2 are connected in series, are connected in parallel. And the bridge circuit is constituted so that an AC voltage Ei of frequency fc is supplied on a junction between the resistors R1 and R2, and the junction between the capacitor C1 and the resonator X, and an output voltage Eo is taken out from the junction between the resistor R1 and the resonator X, and the junction between the resistor R2 and the capacitor C1. By setting the values of the resistors R1 and R2 equally, and setting the absolute values of the impedances of the resonator X, and the capacitor C1 at the frequency fc in equal to the R1 and R2, the phase of the voltage Eo leading by 90 deg. of that of the voltage Ei is generated. The bridge circuit is operated as a phase shifter assumed as linear against the change of a frequency, in a frequency range between the series resonation and the parallel resonation of thc resonator X, and a quadrature detection circuit in which no frequency adjustment is required, can be obtained.

Inventors

• 👤 Muneyoshi Hirano
• 👤 平野　宗義
• 👤 Shoichi Henmi
• 👤 逸見　彰一

Bibliographic Details