Frequency modulation system and method
AssigneeZarlink Semiconductor Inc.
InventorPeter Edward Chadwick
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Abstract
A frequency modulation system is disclosed which includes a voltage-controlled oscillator (VCO) 43 and a phase detector 47 configured to receive an output signal from the VCO. The phase detector is arranged to output an error signal representing the phase difference between the signal from the VCO and a reference signal. The system also includes control means 62 arranged to monitor the error signal to derive an indication of the frequency deviation of the VCO, and, in accordance with this derivation, to maintain the frequency deviation of the VCO substantially constant.
Claims13
A frequency modulation system comprising:
- a voltage controlled oscillator (VCO),
- a phase detector,
- a reference source, and
- a control circuit
- wherein the phase detector produces an error signal output representing the phase difference between an output signal from the VCO and the reference source and wherein the control circuit monitors the error signal (a) to derive an indication of the frequency deviation of the VCO, and, in accordance with the derivation, (b) to maintain the frequency deviation of the VCO substantially constant.
A frequency modulation system comprising:
- a voltage controlled oscillator (VCO) producing an output signal,
- a reference signal source producing a reference signal,
- a phase detector producing an output error signal based on the phase difference between the output signal from the VCO and the reference signal from the reference signal source,
- a modulation signal source,
- an adder combining a signal from the modulation signal source and the error signal from the phase detector to generate a signal for controlling the frequency of the output signal from the VCO, and
- a control circuit configured (a) to receive the error signal from the phase detector and to derive an indication of the frequency deviation of the VCO;
- and (b) to vary the output from the adder in accordance with the derived frequency deviation thereby to maintain the frequency deviation of the VCO substantially constant.
A frequency modulation system comprising:
- a voltage controlled oscillator (VCO),
- a phase detector for generating an error signal based on the detected phase difference between the output signal from the VCO and a fixed frequency reference signal,
- an adder for summing a modulating input signal and the error signal to generate a signal for controlling the output frequency of the VCO, and
- control means configured (a) to receive the error signal and to derive a controlling signal that is proportional to the frequency deviation of the VCO, and (b) to vary the output from the summing means, using the controlling signal, to maintain the frequency deviation of the VCO substantially constant.
A method for performing frequency modulation in a system including a voltage controlled oscillator (VCO), a phase detector for generating an error signal based on the detected phase difference between an output signal from the VCO and a reference signal, and means for summing a modulating input signal and the error signal to generate a signal for controlling the output frequency of the VCO, the method comprising the steps of:
- monitoring the error signal and deriving therefrom an estimate of the frequency deviation exhibited by the VCO, and
- controlling the output of the summing means in accordance with the estimated frequency deviation such that the frequency deviation of the VCO is maintained substantially constant.
Dependencies are inferred from the claim text.