PHASE TO DIGITAL CONVERTER IN ALL DIGITAL PHASE LOCKED LOOP
First Claim
1. A method of phase to digital conversion, the method comprising:
- initiating a first pulse based on an earlier arriving edge of one of a reference clock and an oscillator signal;
coupling the first pulse through a delay line;
determining a conversion termination signal based on a later arriving edge of one of the reference clock and the oscillator signal; and
determining a digital value of a phase difference between the reference clock and the oscillator signal based on a transition of the first pulse through the delay line.
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Abstract
A phase to digital converter, all digital phase locked loop, and apparatus having an all digital phase locked loop are described herein. The phase to digital converter includes a phase to frequency converter driving a time to digital converter. The time to digital converter determines a magnitude and sign of the phase differences output by the phase to frequency converter. The time to digital converter utilizes tapped delay lines and looped feedback counters to enable measurement of small timing differences typical of a loop tracking process and large timing differences typical of an loop acquisition process. The tapped delay lines permit the measurement of fractions of a reference period and enable lower power operation of the phase to digital converter by reducing requirements on the speed of the reference clock.
105 Citations
44 Claims
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1. A method of phase to digital conversion, the method comprising:
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initiating a first pulse based on an earlier arriving edge of one of a reference clock and an oscillator signal; coupling the first pulse through a delay line; determining a conversion termination signal based on a later arriving edge of one of the reference clock and the oscillator signal; and determining a digital value of a phase difference between the reference clock and the oscillator signal based on a transition of the first pulse through the delay line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of phase to digital conversion, the method comprising:
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generating at least one phase to frequency detection signal based on transitions of an oscillator signal and transitions of a reference clock; generating a signal pulse based on the at least one phase to frequency conversion signal; and generating a digital value of a phase difference based on a transition of the signal pulse through a delay line. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of phase to digital conversion, the method comprising:
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receiving an oscillator signal; receiving a reference clock; generating at least one phase to frequency detection signal including an UP signal and a DOWN signal based on transitions of the oscillator signal and transitions of the reference clock; generating a read signal based on the UP signal and the DOWN signal; generating a first signal pulse based on the UP signal; generating a second pulse signal based on the DOWN signal; coupling the first signal pulse to a first delay line; coupling the second pulse signal to a second delay line; counting a number of full transitions of one of the first signal pulse or second signal pulse through its respective delay line based on transitions of the UP signal relative to the DOWN signal; and determining a digital value of a phase difference based on at least one of the number or a partial transition of one of the first signal pulse or the second signal pulse through the respective first delay line and second delay line. - View Dependent Claims (20, 21, 22)
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23. A phase to digital converter comprising:
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a path selection multiplexer configured to receive a reference clock signal at a first input and an oscillator signal at a second input, and further configured to output one of the reference clock signal or oscillator signal based on a control input signal; a first pulse generator having a trigger input coupled to the output of the path selection multiplexer; a loop multiplexer configured to receive a pulse generator output at a first input and a delayed pulse signal at the second input, and configured to output one of the pulse generator output or the delayed pulse signal based on a loop control signal; a delay line coupled to the output of the loop multiplexer and configured to output the delayed pulse signal, and further configured to indicate a fractional pulse transition upon receipt of a conversion termination signal; and a counter configured to count a number of pulses output by the delay line and configured to output the number upon receipt of the conversion termination signal. - View Dependent Claims (24, 25, 26, 27, 28)
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29. A phase to digital converter comprising:
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a first signal processing path configured to determine a magnitude of a phase difference between an oscillator signal and a reference clock based at least one of a fractional transition of a pulse through a delay line and a number of full transitions of the pulse through the delay line; and a sign generator configured to receive the oscillator signal and the reference clock and configured to determine a sign of the phase difference.
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30. A phase to digital converter comprising:
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a phase to frequency detector configured to generate an UP signal and a DOWN signal based on an oscillator signal and a reference clock; a pulse generator coupled to the phase to frequency detector and configured to generate a pulse signal based on one of the UP signal and the DOWN signal; a tapped delay line coupled to the pulse generator; a counter configured to increment based on an output of the delay line; a register coupled to the tapped delay line; and a read control generator configured to generate a read signal based on the UP signal and the DOWN signal, and configured to latch a digital value of a phase difference in at least one of the register or the counter. - View Dependent Claims (31, 32, 33, 34, 35, 36)
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37. A phase to digital converter comprising:
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means for generating a phase to frequency detection signal including an UP signal and a DOWN signal based on transitions of an oscillator signal and transitions of a reference clock; means for generating a conversion Start signal and a conversion Stop signal based on the UP signal and the DOWN signal; means for generating a pulse based on one of the UP signal and the DOWN signal; means for delay coupled to the means for generating the pulse; means for counting coupled to an output of the means for delay; and means for converting a time to a digital value of a phase difference based on the Start signal and the Stop signal and further based on an output of the means for counting and a fractional transition of the pulse through the means for delay. - View Dependent Claims (38, 39, 40)
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41. An all digital phase locked loop (ADPLL) comprising:
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a digital controlled oscillator (DCO); a digital divider having an input coupled to the DCO and an output configured to provide a digital divided output signal; a phase to frequency detector having a first input coupled to a reference oscillator clock and a second input coupled to the output of the digital divider, the phase to frequency detector configured to generate an UP signal and a DOWN signal based on the digital divided output signal and the reference oscillator clock; a phase to digital converter having a first input receiving the UP signal, a second input receiving the DOWN signal, and a third input receiving the reference oscillator clock, the phase to digital converter configured to generate a pulse signal based on one of the UP signal or the DOWN signal and further configured to determine a digital value of a phase difference between the digital divided output signal and the reference oscillator clock based on at least one of full transitions of the pulse signal through a delay line and partial transitions of the pulse through the delay line; and a digital loop filter having an input coupled to an output of the phase to digital converter and an output coupled to a control input of the DCO. - View Dependent Claims (42, 43, 44)
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Specification