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US 3,944,949 AGranted
Frequency modulator
AssigneeAmpex Corporation
InventorWilliam Frederic Herzog
Life of this patent
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Abstract
A frequency modulator includes a capacitor, a controlled current source, and a bistable circuit. The current source and bistable circuit operate to alternately vary the charge in opposite directions on the capacitor. The frequency of opposite charge variation is controlled by the amplitude of the input signal applied to the current source. A control circuit coupled to the capacitor and the bistable circuit varies the frequency of opposite charge variation to provide a linear frequency versus input signal amplitude.
Claims9
A frequency modulator comprising;
- a capacitor;
- a controlled current source coupled to said capacitor and responsive to an applied modulating signal for varying the charge on it in a first direction at a rate dependent upon said applied modulating signal;
- a bistable circuit coupled to said capacitor and responsive to the charge thereon to be switched to each of its two stable states, said current source being coupled to vary the charge on said capacitor in a first direction when said bistable circuit is in a first of its two stable states, said bistable circuit coupled to vary the charge on said capacitor in a second direction opposite said direction when in a second of its two stable states, said bistable circuit having a control terminal for controlling the frequency of switching between its stable states;
- and,
- a control means coupled between said capacitor and said control terminal for controlling the stable state switching frequency dependent on the rate of charge variation provided by said current source.
2 more elements
Dependencies are inferred from the claim text.