Dual mode phase detection
First Claim
1. A method of measuring a phase difference for use in a phase locked loop (PLL) comprising a binary phase detector (BPD), a time-to-digital converter (TDC) and a signal generator, the phase difference being that between a reference signal and a generated signal output from the signal generator, the method comprising:
- inputting the reference signal and the generated signal into the TDC;
measuring the magnitude of the phase difference at the TDC;
if the measured magnitude of the phase difference is less than a threshold value, operating the PLL according to a first operational mode in which the output of the BPD controls the signal generator; and
if the measured magnitude of the phase difference is greater than the threshold value, operating the PLL according to a second operational mode in which the output of the TDC and the BPD controls the signal generator, wherein the PLL further comprises a loop filter, and the method further comprises altering the gain of the loop filter in dependence on the measured phase difference, and wherein a dynamic function unit determines the gain of the loop filter as a function of the magnitude of the measured phase difference.
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Accused Products
Abstract
A method of measuring a phase difference for use in a phase locked loop (PLL) that includes a binary phase detector (BPD), a time-to-digital converter (TDC) and a signal generator, the phase difference being that between a reference signal and a generated signal output from the signal generator. The method includes inputting the reference signal and the generated signal into the TDC; measuring the magnitude of the phase difference at the TDC; if the measured magnitude of the phase difference is less than a threshold value, operating the PLL according to a first operational mode in which the output of the BPD controls the signal generator; and if the measured magnitude of the phase difference is greater than the threshold value, operating the PLL according to a second operational mode in which the output of the TDC and the BPD controls the signal generator.
21 Citations
16 Claims
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1. A method of measuring a phase difference for use in a phase locked loop (PLL) comprising a binary phase detector (BPD), a time-to-digital converter (TDC) and a signal generator, the phase difference being that between a reference signal and a generated signal output from the signal generator, the method comprising:
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inputting the reference signal and the generated signal into the TDC; measuring the magnitude of the phase difference at the TDC; if the measured magnitude of the phase difference is less than a threshold value, operating the PLL according to a first operational mode in which the output of the BPD controls the signal generator; and if the measured magnitude of the phase difference is greater than the threshold value, operating the PLL according to a second operational mode in which the output of the TDC and the BPD controls the signal generator, wherein the PLL further comprises a loop filter, and the method further comprises altering the gain of the loop filter in dependence on the measured phase difference, and wherein a dynamic function unit determines the gain of the loop filter as a function of the magnitude of the measured phase difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for measuring a phase difference for use in a phase locked loop (PLL) comprising a binary phase detector (BPD), time-to-digital converter (TDC) and a signal generator, the phase difference being that between a reference signal and a generated signal output from the signal generator, wherein:
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the TDC is configured to receive the reference signal and the generated signal and to measure the phase difference between these signals; if the measured phase difference is less than a threshold value, the apparatus operates the PLL according to a first operational mode in which the output of the BPD controls the signal generator; and if the measured phase difference is greater than the threshold value, the apparatus operates the PLL according to a second operational mode in which the output of the BPD and the TDC controls the signal generator, wherein the apparatus further comprises a loop filter, the loop filter having a gain that is alterable in dependence upon the measured magnitude of the phase difference, and wherein the apparatus further comprises a dynamic function unit that determines the gain of the loop filter as a function of the measured phase difference. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification