| 摘要 |
PURPOSE: To eliminate the need for a varactor diode from a voltage-controlled oscillator by varying the effective variation amount of capacitance in a resonance circuit so that the resonance frequency of the resonance circuit may be varied nearly linearly by means of the control voltage of the oscillator. CONSTITUTION: In response to random noise, a transistor 4 supplies an output voltage to the load resistor R6 of its collector circuit and a driving voltage to the base of a transistor Q2. When transistors Q3 and Q4 are conducted, the AC emitter current of the transistor Q2 is separated between the emitter- collector paths of the transistors Q3 and Q4 after passing through a serial resonance circuit of an inductance L0 and a capacitor C0. When both the transistors Q3 and Q4 are turned on, in addition, the ratio between the collector currents of leads IIN1 and IIN2 decides the capacitance capacity of a capacitor CX and the amount of capacitive reactance and oscillation frequency of the serial resonance circuit are decided. Therefore, the current of the transistor Q3 is varied more linearly by the control voltage.
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