Method of low power PLL for low jitter demanding applications
First Claim
1. A system comprising a phase locked loop and an activation circuit;
- wherein the phase locked loop comprises;
an oscillator adapted to output an output signal having an output frequency in response to a control signal;
a frequency divider, coupled to the oscillator, adapted to generate a feedback signal that has a feedback frequency that is a fraction of the output frequency;
a phase detector, coupled to the frequency divider and to a reference signal source, adapted to output a phase error signal that represents a phase difference between the feedback signal and the reference signal;
a control circuit, adapted to receive the phase error signal and to generate the control signal;
a memory circuit, adapted to store the control signal; and
an activation circuit, adapted to activate the memory circuit and the oscillator; and
to deactivate the frequency divider, the phase detector and the control circuit during deactivation periods and to activate the frequency divider, the phase detector and the control circuit during activation periods;
wherein a timing relationship between a deactivation period and an activation period is responsive to an output signal jitter limitation and to a power consumption limitation.
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Accused Products
Abstract
A system that includes a phase locked loop and an activation circuit; wherein the phase locked loop includes an oscillator, a frequency divider, a phase detector, a control circuit, and a memory circuit. The activation circuit is adapted to activate the memory circuit and the oscillator; to deactivate the frequency divider, the phase detector and the control circuit during deactivation periods and to activate the frequency divider, the phase detector and the control circuit during activation periods. The timing relationship between a deactivation period and an activation period is responsive to an output signal jitter limitation and to a power consumption limitation.
3 Citations
20 Claims
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1. A system comprising a phase locked loop and an activation circuit;
wherein the phase locked loop comprises; an oscillator adapted to output an output signal having an output frequency in response to a control signal; a frequency divider, coupled to the oscillator, adapted to generate a feedback signal that has a feedback frequency that is a fraction of the output frequency; a phase detector, coupled to the frequency divider and to a reference signal source, adapted to output a phase error signal that represents a phase difference between the feedback signal and the reference signal; a control circuit, adapted to receive the phase error signal and to generate the control signal; a memory circuit, adapted to store the control signal; and an activation circuit, adapted to activate the memory circuit and the oscillator; and
to deactivate the frequency divider, the phase detector and the control circuit during deactivation periods and to activate the frequency divider, the phase detector and the control circuit during activation periods;wherein a timing relationship between a deactivation period and an activation period is responsive to an output signal jitter limitation and to a power consumption limitation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for power consumption reduction, the method comprises:
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storing at a memory circuit a control signal obtained during an activation period of a frequency divider, a phase detector and a control circuit of a phase locked loop; deactivating the frequency divider, the phase detector and the control circuit of the phase locked loop while activating the control circuit and the oscillator during a deactivation period that follows the activation period so as to generate an output signal that is responsive to a control signal stored at the memory circuit; wherein a timing relationship between the deactivation period and the activation period is responsive to an output signal jitter limitation and to a power consumption limitation. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification