Voltage controlled oscillator with jitter correction
First Claim
1. A method of operating a signal controlled oscillator that provides an output clock having an actual period, the method comprising:
- directly measuring successive actual periods of the output clock;
generating a control signal representative of deviations in the successive actual periods of the output clock; and
adjusting the actual period of the output clock in response to the control signal.
1 Assignment
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Accused Products
Abstract
A phase controller is coupled to a voltage-controlled oscillator (VCO) in a feedback configuration, thereby reducing the phase noise introduced by the VCO. As a result, circuits using the VCO, such as phase-locked loops or delay locked loops, will exhibit reduced jitter in the resulting output signals. In one embodiment, the phase controller measures successive actual periods of the VCO output clock, and in response, generates a control voltage representative of deviations in the successive actual periods of the VCO output clock. The phase controller transmits the control voltage to the VCO as a feedback control voltage. The VCO adjusts the actual period of the VCO output clock in response to the control voltage. More specifically, the VCO adjusts the actual period of the VCO output clock such that deviations in the successive actual periods of the VCO output clock are reduced.
21 Citations
26 Claims
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1. A method of operating a signal controlled oscillator that provides an output clock having an actual period, the method comprising:
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directly measuring successive actual periods of the output clock;
generating a control signal representative of deviations in the successive actual periods of the output clock; and
adjusting the actual period of the output clock in response to the control signal. - View Dependent Claims (2, 3, 4, 5, 6)
routing the output clock to a phase comparator;
routing a reference clock signal to the phase comparator;
generating an error signal representative of the difference between the output clock and the reference clock signal; and
controlling the signal controlled oscillator in response to the error signal.
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7. A method of operating a signal controlled oscillator that provides an output clock having an actual period, the method comprising:
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measuring successive actual periods of the output clock;
generating a control signal representative of deviations in the successive actual periods of the output clock;
filtering the control signal using a high-pass filter; and
adjusting the actual period of the output clock in response to the control signal.
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8. A method of operating a signal controlled oscillator that provides an output clock having an actual period, the method comprising:
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measuring successive actual periods of the output clock;
generating a control signal representative of deviations in the successive actual periods of the output clock, wherein the control signal is generated by;
generating a first signal having a magnitude corresponding with a first half period of the output clock;
generating a second signal having a magnitude corresponding with a second half period of the output clock; and
generating the control signal in response to the first signal and the second signal; and
adjusting the actual period of the output clock in response to the control signal. - View Dependent Claims (9, 10, 11, 12)
charging the capacitor when the first signal or the second signal exceeds the control signal; and
discharging the capacitor when neither the first signal nor the second signal exceeds the control signal.
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13. A signal controlled oscillator comprising:
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means for directly measuring successive actual periods of an output clock provided by the signal controlled oscillator;
means for generating a control signal representative of deviations in the successive actual periods of the output clock; and
means for adjusting the actual period of the output clock in response to the control signal. - View Dependent Claims (14, 15)
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16. A signal controlled oscillator system comprising:
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a signal controlled oscillator configured to generate an output clock having an actual period in response to an input signal;
a phase controller coupled to receive the output clock, the phase controller being configured to generate a control signal directly in response to the output clock, wherein the control signal is representative of cycle-to-cycle deviations in the actual period of the output clock; and
a feedback line for transmitting the control signal to the signal controlled oscillator.
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17. A signal controlled oscillator system comprising:
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a signal controlled oscillator configured to generate an output clock having an actual period in response to an input signal;
a phase controller coupled to receive the output clock, the chase controller being configured to generate a control signal representative of cycle-to-cycle deviations in the actual period of the output clock; and
a feedback line for transmitting the control signal to the signal controlled oscillator, wherein the signal controlled oscillator includes a circuit for combining the control signal with the input signal to create an internal input signal, the signal controlled oscillator generating the output clock in response to the internal input signal.
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18. A The signal controlled oscillator system comprising:
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a signal controlled oscillator configured to generate an output clock having an actual period in response to an input signal;
a phase controller coupled to receive the output clock, the phase controller being configured to generate a control signal representative of cycle-to-cycle deviations in the actual period of the output clock, wherein the phase controller includes an amplifier configured to generate a pair of complementary clock signals in response to the output clock; and
a feedback line for transmitting the control signal to the signal controlled oscillator. - View Dependent Claims (19, 20, 21, 22, 23)
a first capacitor;
a second capacitor;
a resistor;
a first transistor coupling the first capacitor to the resistor, wherein the first transistor is controlled by a first one of the complementary clock signals; and
a second transistor coupling the second capacitor to the resistor, wherein the second transistor is controlled by a second one of the complementary clock signals.
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24. A signal controlled oscillator system of comprising:
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a signal controlled oscillator configured to generate an output clock having an actual period in response to an input signal;
a phase controller coupled to receive the output clock, the phase controller being configured to generate a control signal representative of cycle-to-cycle deviations in the actual period of the output clock;
a feedback line for transmitting the control signal to the signal controlled oscillator;
a phase comparator coupled to receive the output clock and a reference clock signal, the phase comparator being configured to generate an error signal representative of the difference between the output clock and the reference clock signal; and
a loop filter coupled the phase comparator, the loop filter being configured to generate the input signal in response to the error signal.
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25. A method of operating a signal controlled oscillator that generates an output clock, the method comprising:
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measuring a first period of the output clock;
measuring a second period of the output clock, wherein the first period is a previous period with respect to the second period;
generating a feedback signal representative of a deviation between the first and second periods; and
adjusting a third period of the output clock in response to the feedback signal. - View Dependent Claims (26)
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Specification