| 摘要 |
A highly stable, tunable oscillator circuit includes a crystal oscillator providing a reference pulse signal of frequency Fco, a voltage-to-frequency converter responsive to a control voltage for providing a control pulse signal of frequency Fv substantially lower than Fco, a toggle circuit receiving the reference signal and providing a first and a second complementary signals, each having a frequency Fco/2 and the same pulse-width as the reference signal, a flip-flop circuit receiving the reference signal, the control signal and the first complementary signal and providing a pulse signal having frequency Fv and a pulse-width equal to the period of the reference signal, and synchronized with the first and second complementary signals. The signal provided by the flip-flop circuit is logically combined with the first complementary signal in and AND gate. The output of the AND gate is then logically combined with the second complementary signal in an OR gate to derive a combined signal of frequency (Fco/2)+Fv. The combined signal is received by a frequency divider network which divides the frequency of the combined signal by an integer N and provides an output signal at a desired frequency. By selecting the frequencies of the reference, control and output signal such that Fco>>Fv>>Fo, a highly stable, smoothly tunable output signal is obtained.
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