| 摘要 |
1,173,885. Voltage-controlled oscillators. GENERAL ELECTRIC CO. 15 Feb., 1968 [3 April, 1967], No. 7526/68. Heading H3A. A voltage-controlled oscillator comprises a tuned circuit including an inductance 14 both ends of which are connected to earth through respective transistors 10 and 11 which are rendered conductive alternately at a frequency much greater than that of the oscillator so that the effective inductance, and therefore the output frequency, depends on the on-off ratio of the switching waveform applied to the transistors. The oscillator may be used to demodulate an input signal of the vestigial sidebandtype in a balanced demodulator 2 which produces an error signal on line 5 if the oscillator is not in the required phase. This error signal is fed to a differential amplifier 52 which provides outputs on lines 50 and 51 which control the on-off ratio (but not the frequency) of a freerunning multivibrator 25 which provides the switching waveforms to transistors 10 and 11. |
