VOLTAGE CONTROL TYPE OSCILLATOR

摘要

PURPOSE:To increase the resistance to the fluctuation of the power supply voltage and to reduce the power consumption, by providing a phase control circuit to the feedback circuit of an oscillator to control the oscillating frequency by making use of the fact that a synchronizing wave detecting circuit contains a pi/2 phase shifter. CONSTITUTION:A resonance circuit containing a coil 9 and a capacitor C10 is connected between the transistors (TR)7 and 8 which form a differential amplifier. The voltage between these two collectors is used to the 1st output. Then a phase shifter is constituted by capacitors C11, C13 and TR12, TR14 to give a pi/2 phase shift to the above-mentioned output. The output of the phase shifter is used to the 2nd output. An amplitude/polarity control circuit comprising the TR15-TR20 and a resistance 21 receives the 2nd output and controls the amplitude and the polarity with the external voltage. This controlled output and the 1st output are added with each other and synthesized to be fed back to the input of the above-mentioned differential amplifier.