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US 10,187,197 B2Granted
Optical clock recovery using feedback phase rotator with non-linear compensation
AssigneeCiena Corporation
InventorsSadok Aouini, Naim Ben-Hamida, Christopher Kurowski, Lukas Jakober
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Abstract
A method for clock recovery that may include obtaining an output signal from a phase locked loop (PLL) device. The method may further include determining, using a digital phase detector, the output signal, and a transmitter clock signal, an amount of phase difference between the output signal and the transmitter clock signal. The method may further include filtering, using a phase rotator and a digital accumulator, a portion of the amount of phase difference from the output signal to generate a filtered signal.
Claims20
A receiver apparatus, comprising:
- a phase locked loop (PLL) device that includes
- an analog phase detector configured to receive a reference signal, and
- a voltage-controlled oscillator (VCO) device, wherein the VCO device is configured to generate, based on the reference signal, an output signal;
- a phase rotator coupled to the VCO device and the analog phase detector;
- a digital phase detector coupled to the VCO device, the digital phase detector configured to determine an amount of phase difference between a transmitter clock signal and the output signal;
- a digital accumulator coupled to the digital phase detector, wherein the phase rotator and the digital accumulator are configured, using the amount of phase difference between the transmitter clock signal and the output signal, to filter a portion of the amount of phase difference from the output signal to generate a filtered signal for transmission to the analog phase detector;
- and
- a lookup table circuit coupled to the digital accumulator,
- wherein the lookup table circuit is configured to generate a control signal based on a value of the amount of phase difference between the transmitter clock signal and the output signal, and
- wherein the control signal is configured to produce, using the phase rotator, a predetermined phase shift in the filtered signal provided as a feedback signal within the PLL device.
7 more elements
A receiver apparatus, comprising:
- a phase locked loop (PLL) device that includes
- an analog phase detector configured to obtain a reference signal, and
- a voltage-controlled oscillator (VCO) device, wherein the VCO device is configured to generate, based on the reference signal, an output signal;
- a phase rotator coupled to the VCO device and the analog phase detector;
- a first digital phase detector coupled to the VCO device, the first digital phase detector being configured to determine an amount of phase difference between a transmitter clock signal and the output signal;
- a digital accumulator coupled to the first digital phase detector, wherein the phase rotator and the digital accumulator are configured, using the amount of phase difference between the transmitter clock signal and the output signal, to filter a portion of the amount of phase difference from the output signal to generate a filtered signal for transmission to the analog phase detector;
- a delay element coupled to the phase rotator and the analog phase detector;
- a second digital phase detector coupled to the delay element and the phase rotator, the second digital phase detector being configured to determine an amount of PLL noise based on the reference signal and the filtered signal;
- and
- a digital filter coupled to the second digital phase detector,
- wherein the delay element and the digital filter are configured, using the amount of PLL noise, to reduce a portion of the amount of PLL noise from the filtered signal.
8 more elements
A receiver apparatus, comprising:
- a phase locked loop (PLL) device that includes
- an analog phase detector configured to obtain a reference signal, and
- a voltage-controlled oscillator (VCO) device, wherein the VCO device is configured to generate, based on the reference signal, an output signal;
- a phase rotator coupled to the VCO device and the analog phase detector;
- a digital phase detector coupled to the VCO device, the digital phase detector being configured to determine an amount of phase difference between a transmitter clock signal and the output signal;
- a digital accumulator coupled to the digital phase detector, wherein the phase rotator and the digital accumulator are configured, using the amount of phase difference between the transmitter clock signal and the output signal, to filter a portion of the amount of phase difference from the output signal to generate a filtered signal for transmission to the analog phase detector;
- a reference clock source configured to generate the reference signal;
- and
- a frequency counter coupled to the VCO device and the reference clock source,
- wherein the frequency counter is configured to determine a frequency difference between a frequency of the reference clock source and a frequency of the VCO device, and
- wherein the frequency counter is further configured to generate a control signal configured to change the frequency of the reference clock source based on the frequency difference.
8 more elements
Dependencies are inferred from the claim text.