| 摘要 |
PURPOSE:To obtain an output pulse whose duty ratio is 50% by providing a detection circuit detecting respectively an average value of two inverting/non-inverting outputs of an oscillator and a feedback circuit feeding back the output of the differential amplifier amplifying the difference between the two mean values to the oscillator so as to make the two mean values coincident with each other. CONSTITUTION:The oscillator using an emitter coupling a stable multivibrator, the detection circuit detecting respectively the mean values V1', V2' of two outputs V1, V2 (inverting/non-inverting) of the oscillator, a differential amplifier IC1 amplifying the difference between the said two mean values V1', V2', and the feedback circuit feeding back the output of the differential amplifier IC1 to the said oscillator so as to make the said two mean values V1', V2' are made coincident, are provided. For example, a low pass filter comprising a resistor R8, a capacitor C1, a resistor R9 and a capacitor C2, and the differential amplifier IC1 are added to a conventional circuit, and two outputs of the differential amplifier IC1 are inputted respectively to differential transistor (TR) pairs Q11, Q12. Further, a TR Q13 and a resistor R12 constitute a current source, which is used for the current to TRs Q11, Q12. Then the output pulse having 50% duty ratio is obtained and suitable for the use for generating a clock for an FM modulator or a timing extraction PLL.
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