| 摘要 |
PURPOSE:To obtain an oscillating circuit which is suitable to an analog integrated circuit that can be driven with a relatively low voltage and low current, by externally connecting a piezoelectric vibrator only commonly with an earthing terminal and another terminal as a connecting terminal. CONSTITUTION:DC biases for operation are given in such a way that the base current of a transistor (TR) 16 is given from a constant-current source 34 and the base voltage of a TR 15 is supplied from a constant-voltage source 23, and then, the emitter currents of the TRs 15 and 16 are supplied from a current source 19. Since the equivalent resistance of a TR 18 and the resistance value of a resistance 22 are very weak, the TRs 15 and 16 almost work as a base earthing amplification stage and emitter follower input stage, respectively. Therefore, a high treble cut-off frequency can be taken than one stage of ordinary transistor amplification does. Resonant signals produced from an externally fitted piezoelectric vibrator 1 are amplifier in current by means of the TR 16 after passing through a ladder type high-pass filter composed of capacitors 20, 30, and 31 and resistances 32 and 33 and, after they are further amplified in voltage by the TR 15, fetched from the collector of the TR 15 as oscillating outputs. At the same time, the resonant signals are fed back to the vibrator 1 as exciting signals, and thus, the oscillation is continued.
|
