Data reproduction circuit

• US 20070064850A1
• Filed: 02/23/2006
• Published: 03/22/2007
• Est. Priority Date: 09/16/2005
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Tamura, Hirotaka
• Granted Patent: US 7,940,873 B2
• Time in Patent Office: Days
• US Class Current: 375/355
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop

Abstract

This is a data reproduction circuit for receiving data and reproducing the data and its clock which comprises an over-sampling determination circuit for sampling the received data by a clock with frequency higher than the data rate of the received data and converting the sampled data into digital signals, a circuit for selecting and outputting the reproduced data, a phase error detection circuit for detecting a phase error from its timing deviation with the received data, based on the reproduced clock, a data selection circuit for adjusting its phase, based on the output of the phase error detection circuit, a phase adjustment circuit for adjusting the phase of the reproduced clock to reproduce a new clock and a clock generation circuit for supplying the over-sampling determination circuit and the data selection circuit with the newly reproduced clock.

Claims

1. A data reproduction circuit for receiving data and reproducing data and a clock, comprising:

an over-sampling determination circuit for sampling the received data by a clock with a frequency higher than a data rate of the received data, based on a first reproduced clock and converting it into digital signals;

a data selection circuit with a circuit for selecting and outputting reproduced data by determining the digital signals generated by the over-sampling determination circuit in a timing based on the first reproduced clock, a phase error detection circuit for detecting a phase error from its timing difference with the received data, based on the first reproduced clock and a circuit for outputting an adjustment signal in order to adjust its phase, based on the output of the phase error detection circuit; and

a clock generation circuit with a phase adjustment circuit in which the adjustment signal adjusts a phase of a second reproduced clock in a state at least immediately before the first reproduced clock and which generates the first reproduced clock and a circuit for supplying the first reproduced clock to the over-sampling determination circuit and the data selection circuit.

2. The data reproduction circuit according to claim 1, wherein

the phase error detection circuit comprises

a phase/frequency error detection circuit with a circuit for detecting a frequency error from its timing difference with the received data, based on the first reproduced clock, and

the phase adjustment circuit comprises a frequency adjustment circuit with a circuit for also adjusting the frequency error.

3. The data reproduction circuit according to claim 1, wherein

the frequency adjustment circuit is a phase interpolator, and a digital filter for generating a weighting signal which controls the phase interpolator, based on the adjustment signal of the phase/frequency error detection circuit is provided.

11. The data reproduction circuit according to claim 1, wherein

the phase error detection circuit detects a data change point, based on the over-sampled data and the first reproduced clock, generates a phase signal from the change point, converts the movement of the phase signal into a pointer signal and outputs the pointer signal as an adjustment signal for adjusting a phase.

12. The data reproduction circuit according to claim 1, wherein

the data selection circuit performs a pipeline process.

13. The data reproduction circuit according to claim 1, wherein

the adjustment signal is generated by a charge pump and a loop filter.

14. The data reproduction circuit according to claim 2, wherein

the frequency/phase error detection circuit detects a data change point, based on the over-sampled data and the first reproduced clock, generates a phase signal from the change point, converts the movement of the phase signal into a pointer signal,

further generates a signal for adjusting a frequency from the pointer signal and outputs it as an adjustment signal for adjusting a phase together with the pointer signal.

15. The data reproduction circuit according to claim 2, wherein

the data selection circuit performs a pipeline process.

16. The data reproduction circuit according to claim 2, wherein

the adjustment signal is generated by a charge pump and a loop filter.

4. A data reproduction circuit for receiving data and reproducing data and a clock, comprising;

a first clock generation circuit for generating a clock for over-sampling data, based on a reference clock;

an over-sampling determination circuit for sampling the received data by a clock with a frequency higher than a data rate of the received data, based on a clock generated by a first clock generation circuit and converting it into digital signals;

a data selection circuit with a circuit for selecting and outputting a reproduced data by determining the digital signals generated by the over-sampling determination circuit in a timing based on the first reproduced clock, a phase/frequency error detection circuit for detecting a phase error and a frequency error from a timing difference with the received data, based on the first reproduced clock and a circuit for outputting a signal for adjusting a phase and a frequency, based on an output of the phase/frequency error detection circuit; and

a second clock generation circuit with a frequency adjustment circuit in which the adjustment signal reflects phase adjustment of a second reproduced clock in a state at least immediately before the first reproduced clock and adjustment of the frequency error and which generates the first reproduced clock and a circuit for supplying the fist reproduced clock to the over-sampling determination circuit and the data selection circuit.

5. The data reproduction circuit according to claim 4, wherein

the frequency adjustment circuit is a phase interpolator, and a digital filter for generating a weighting signal which controls the phase interpolator, based on the adjustment signal of the phase/frequency error detection circuit is provided.

17. The data reproduction circuit according to claim 4, wherein

the phase error detection circuit detects a data change point, based on the over-sampled data and the first reproduced clock, generates a phase signal from the change point, converts the movement of the phase signal into a pointer signal,

further generates a signal for adjusting a frequency from the pointer signal and outputs it as an adjustment signal for adjusting a phase together with the pointer signal.

6. A data reproduction circuit for receiving data and reproducing data and a clock, comprising;

a clock generation circuit for generating a clock for over-sampling the received data, based on a reference clock;

an over-sampling determination circuit for sampling the received data by a clock with a frequency higher than a data rate of the received data and converting it into digital signals;

a data selection circuit with a circuit for selecting and outputting reproduced data by determining the digital signals generated by the over-sampling determination circuit, based on a first reproduced clock and a circuit for generating a signal for controlling a second reproduced clock for generating the first reproduced clock;

a clock selection circuit for selecting the second reproduced clock by the clock supplied by the clock generation circuit and the control signal; and

a phase-locked loop (PLL) circuit for reducing the jitters of the second reproduced clock and generating the first reproduced clock.

7. The data reproduction circuit according to claim 6, wherein

the PLL is an injection-lock PLL with an injection locking voltage-controlled oscillator (VCO).

8. The data reproduction circuit according to claim 7, wherein

the PLL is externally provided with the VCO.

9. The data reproduction circuit according to claim 8, wherein

the VCO is a voltage-controlled crystal oscillator (VXCO) using a crystal oscillation circuit.

10. A data reproduction circuit for receiving data and reproducing data and a clock, comprising;

a determination clock generation circuit for generating a clock for over-sampling the received data, based a reference clock;

an over-sampling determination circuit for sampling the received data by a clock with a frequency higher than a data rate of the received data, based on a sample clock generated by the determination clock generation circuit and converting it into digital signals;

a writing control circuit for adjusting a timing of the sample clock from the determination clock generation circuit;

a first selector circuit for writing and controlling the digital signals into a plurality of buffers, based on an output of the writing control circuit;

a second selector circuit for reading the digital signals from the buffers by a reading signal which selects the digital signals;

a data selection clock generation circuit for generating a reproduced clock for reproducing the data;

a reading control circuit for controlling the reading signal, based on the reproduced clock generated by the data selection clock generation circuit; and

a data selection circuit for selecting and outputting reproduced data by determining the digital signals selected and outputted by the second selector circuit at a timing based on the reproduced clock.