Variable-frequency oscillation circuit

A variable-frequency oscillator circuit comprising:

• (a) a reference oscillator providing a reference pulse signal at a frequency fc;
• (b) voltage-to-frequency converter means responsive to a control voltage for providing a control pulse signal at a frequency fv substantially lower than fc;
• (c) first logic means responsive to the reference signal and the control signal for providing a first pulse signal having a frequency substantially equal to fv and a pulse width substantially equal to 1/fc and synchronized with the reference signal, the first logic means comprising first and second J-K flip-flops each having a clock input, J and K logic inputs, an asynchronous clear input, a nominal output and an inverted output, and a first two-input NAND gate, the clock inputs of the first and second flip-flops being connected to the reference oscillator for receiving the reference signal therefrom, the K and clear inputs of the first flip-flop being connected to the voltage-to-frequency converter means for receiving the control signal therefrom, the K and clear inputs of the second flip-flop being connected to the inverted output of the first flip-flop, the J inputs of the first and second flip-flops being operatively maintained at a "1" logic state, the first two-input NAND gate being connected to receive the nominal output of the first flip-flop and the inverted output of the second flip-flop and providing the first pulse signal;
• (d) second logic means responsive to the reference signal and the first signal for providing a second pulse signal which is substantially the same as the reference signal but with a pulse periodically removed at intervals of 1/fv, the second logic means comprising a second two-input NAND gate and an inverter, the second NAND gate being connected to the reference oscillator through the inverter for receiving the inverted reference signal and to the first NAND gate for receiving the first signal, and providing the second signal;
• and
• (e) frequency divider means responsive to the second signal for dividing the frequency of the second signal by an integral amount to provide an output signal of a desired frequency.