Apparatus and methods for phase synchronization of phase-locked loops
First Claim
1. A radio frequency (RF) communication system comprising:
- a phase-locked loop (PLL) configured to generate one or more output clock signals;
a sampling circuit configured to generate a plurality of samples by sampling the one or more output clock signals based on timing of a reference clock signal;
a phase difference calculation circuit configured to generate a phase difference signal based on the plurality of samples and a tracking digital phase signal representing the phase of the PLL; and
a phase adjustment control circuit configured to provide a phase adjustment to the PLL based on the phase difference signal so as to synchronize the PLL.
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Abstract
Apparatus and methods for phase synchronization of phase-locked loops (PLLs) are provided. In certain configurations, an RF communication system includes a PLL that generates one or more output clock signals and a phase synchronization circuit that synchronizes a phase of the PLL. The phase synchronization circuit includes a sampling circuit that generates samples by sampling the one or more output clock signals based on timing of a reference clock signal. Additionally, the phase synchronization circuit includes a phase difference calculation circuit that generates a phase difference signal based on the samples and a tracking digital phase signal representing the phase of the PLL. The phase synchronization circuit further includes a phase adjustment control circuit that provides a phase adjustment to the PLL based on the phase difference signal so as to synchronize the PLL.
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Citations
25 Claims
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1. A radio frequency (RF) communication system comprising:
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a phase-locked loop (PLL) configured to generate one or more output clock signals; a sampling circuit configured to generate a plurality of samples by sampling the one or more output clock signals based on timing of a reference clock signal; a phase difference calculation circuit configured to generate a phase difference signal based on the plurality of samples and a tracking digital phase signal representing the phase of the PLL; and a phase adjustment control circuit configured to provide a phase adjustment to the PLL based on the phase difference signal so as to synchronize the PLL. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of phase synchronization in a frequency synthesizer, the method comprising:
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generating one or more output clock signals using a phase-locked loop (PLL); sampling the one or more output clock signals based on timing of a reference clock signal to generate a plurality of samples; generating a phase difference signal based on the plurality of samples and a tracking digital phase signal representing a phase of the PLL; and synchronizing the PLL by providing a phase adjustment that is based on the phase difference signal. - View Dependent Claims (20, 21, 22, 23, 24)
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25. A massive multiple-input multiple-output (MIMO) system comprising:
a plurality of frequency synthesizers configured to generate a plurality of local oscillator signals based on timing of a common reference clock signal, wherein a first frequency synthesizer of the plurality of frequency synthesizers comprises; a phase-locked loop (PLL) configured to generate one or more local oscillator signals of the plurality of local oscillator signals; a sampling circuit configured to generate a plurality of samples by sampling the one or more local oscillator signals based on timing of the common reference clock signal; a phase difference calculation circuit configured to generate a phase difference signal based on the plurality of samples and a tracking digital phase signal representing the phase of the PLL; and a phase adjustment control circuit configured to provide a phase adjustment to the PLL based on the phase difference signal.
Specification