Low distortion oscillator circuit using varactor diodes

The figure above shows a low-distortion oscillator circuit using varactor diodes. The use of varactor diodes (or double varactor diodes) in transistor oscillators can achieve electrical tuning, and can also be made into voltage-controlled oscillators, which are usually used in low-control oscillators.

Inductors and capacitors connected in parallel can form an LC parallel resonant circuit. In the resonant circuit, the varactor diode is essentially equivalent to a variable capacitor. The DC control voltage is added to the varactor diode to fine-tune the junction capacitance of the varactor diode. the size of. Therefore, the DC control voltage can also be said to be a tuning voltage. Changing the control voltage value can change the oscillation frequency of the oscillator.