Phase locked loop (PLL) with linear parallel sampling phase detector
First Claim
1. An apparatus configured to receive an input data signal having a phase and generate an output signal having a plurality of phases comprising:
- a plurality of phase detector circuits each configured to receive said input data signal and to generate a respective phase difference signal, each of said respective phase difference signals corresponding to a phase difference between the phase of said input data signal and a respective phase of said output signal, wherein at least one of said phase detectors includes (i) a first memory element configured to generate a sampled data signal in response to said input data signal, (ii) a function gate configured to generate a first pump signal in response to said input data signal and said sampled data signal, and (iii) a second circuit configured to generate a second pump signal in response to said first pump signal; and
a circuit configured to generate the respective phases of said output signal in response to said phase difference signals.
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Abstract
A parallel sampling phase detector with linear output response. The parallel sampling phase detector for use in data recovery. The device includes a voltage controlled oscillator (VCO) that generates ten separate phase signals using a five stage ring oscillator. Five linear phase detectors are employed in the device, each operating during one of five “window” intervals. The “window” intervals are non-overlapping, and are generated using preselected ones of the VCO output phases. The linear phase detectors each generate, respectively, a variable pulsewidth pump up signal wherein the pulsewidth of the pump up signal is proportional to a phase difference between the input data signal applied to the phase detector, and the output phase signals of the VCO. Each phase detector also generates a pump down signal that has a fixed pulsewidth. A loop filter determines the difference between the pump up and pump down signals and develops a control signal to vary the output frequency and phase of the VCO in accordance therewith. Each phase detector also operates as a deserializer, capturing, during the interval when the respective “window” signal is active, the data signal from the input data stream. The plurality of sampled data signals are captured by a data register, which then outputs an n-bit (5-bit) parallel format data word. The linear phase detector includes means for generating the pump down signal in response to the generation of the pump up signal.
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Citations
22 Claims
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1. An apparatus configured to receive an input data signal having a phase and generate an output signal having a plurality of phases comprising:
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a plurality of phase detector circuits each configured to receive said input data signal and to generate a respective phase difference signal, each of said respective phase difference signals corresponding to a phase difference between the phase of said input data signal and a respective phase of said output signal, wherein at least one of said phase detectors includes (i) a first memory element configured to generate a sampled data signal in response to said input data signal, (ii) a function gate configured to generate a first pump signal in response to said input data signal and said sampled data signal, and (iii) a second circuit configured to generate a second pump signal in response to said first pump signal; and
a circuit configured to generate the respective phases of said output signal in response to said phase difference signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 17, 20, 22)
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11. A parallel sampling phase detector apparatus comprising;
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a plurality of phase detector circuits each configured to receive an input data signal, said phase detector circuits being configured to generate a phase difference signal, each of said phase difference signals corresponding to a phase difference between the phase of said input data signal and a respective phase of an output signal, wherein at least one of said phase detectors includes (i) a first memory element configured to generate a sampled data signal in response to said input data signal, (ii) a function gate configured to generate a pump signal in response to said input data signal and said sampled data signal, and (iii) a second circuit configured to generate a second pump signal in response to said first pump signal;
a loop filter configured to generate a control signal in response to said phase difference signals; and
a voltage controlled oscillator (VCO) configured to generate said output signal in response to said control signal wherein said output signal has a plurality of phases, wherein each phase detector circuit operates according to at least one preselected phase of said VCO output signal. - View Dependent Claims (12, 13, 18)
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14. A method of recovering data from an input data signal comprising the steps of:
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(A) generating, for each one of a plurality of linear output phase detectors, (a) a respective phase difference signal in response to said input data signal, wherein each phase difference signal corresponds to a respective phase difference between the phase of said input data signal and a respective phase of an output signal and at least one of said phase detectors includes (i) a first memory element configured to generate a sampled data signal in response to said input data signal and (ii) a function gate configured to generate a first pump signal in response to said input data signal and said sampled data signal and (b) a second pump signal;
(B) generating the respective phases of said output signal in response to the phase difference signals; and
(C) determining and storing a plurality of bit values during respective bit periods of said input data signal in response to said phases of said output signal. - View Dependent Claims (15, 16, 19, 21)
storing said bit values to thereby form a parallel-bit data word.
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16. The method of claim 14 wherein step (C) includes the substeps of:
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generating a window signal for each linear phase detector in response to preselected phases of said output signal, only one of said window signals being active at a time; and
generating, for each linear phase detector, the sampled data signal when a respective one of said window signals becomes active.
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19. The method according to claim 16, wherein said function gate comprises an enable terminal for receiving said window signal.
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21. The method according to claim 14, wherein (i) said first pump signal comprises a pump up signal and said second pump signal comprises a pump down signal, (ii) at least one of said first and second pump signals have a pulsewidth that varies according to a respective one of said phase differences, and (iii) said phase difference signals comprise said first and second pump signals.
Specification