Clock and data recovery device

1. A clock and data recovery device for reducing loop delay in a bang-bang loop comprising:

an equalizer that compensates for channel loss of input data;

a phase detector that compares a data output from the equalizer with a clock fed back from a voltage controlled oscillator and outputs an up signal and a down signal;

a charge pump that operates according to the up signal and the down signal and outputs a control signal;

a loop filter that removes high-frequency components included in the control signal output from the charge pump;

the voltage controlled oscillator that changes a frequency of the clock and outputs a clock with changed frequency according to the control signal from which the high-frequency components have been removed; and

a data phase adjuster that synchronizes the clock output from the voltage controlled oscillator and the data output from the equalizer by adjusting a phase of the data output from the equalizer by receiving the up signal and the down signal output from the phase detector.

2. The clock and data recovery device of claim 1 , wherein

the phase detector is a bang-bang phase detector.

3. The clock and data recovery device of claim 1 , wherein

the phase detector

outputs the up signal when a phase of the clock fed back from the voltage controlled oscillator is ahead of a phase of the data output from the equalizer, and

outputs the down signal when the phase of the clock fed back from the voltage controlled oscillator is behind the phase of the data output by the equalizer.

4. The clock and data recovery device of claim 3 , wherein

the data phase adjuster comprises

a first capacitor installed between a transmission line connecting the equalizer and the phase detector and a ground,

a first switch installed between the first capacitor and the transmission line,

a second capacitor installed between the transmission line and the ground and connected in parallel with the first capacitor, and

a second switch installed between the second capacitor and the transmission line.

5. The clock and data recovery device of claim 4 , wherein

when both the up signal and the down signal output from the phase detector are at low levels, the first switch is at a closed state and the second switch maintains an open state.

6. The clock and data recovery device of claim 5 , wherein

the data output from the equalizer is delayed by a resistor-capacitor (RC) time corresponding to a capacitance of the first capacitor and transmitted to the phase detector, so that the phase of the data output from the equalizer and the phase of the clock output from the voltage controlled oscillator are synchronized with each other.

7. The clock and data recovery device of claim 5 , wherein

when the up signal output from the phase detector is at a high level, the first switch is at the closed state, and the second switch is switched from the open state to the closed state.

8. The clock and data recovery device of claim 7 , wherein

the data output from the equalizer is delayed by a resistor-capacitor (RC) time corresponding to capacitances of the first capacitor and the second capacitor connected in parallel and transmitted to the phase detector.

9. The clock and data recovery device of claim 8 , wherein

since the first capacitor and the second capacitor are connected in parallel to increase a total capacitance, a resistor-capacitor (RC) delay of the data output from the equalizer is increased compared to a case where both the up signal and the down signal output from the phase detector are at the low levels, so that the phase of the data output from the equalizer and the phase of the clock output from the voltage controlled oscillator are synchronized with each other.

10. The clock and data recovery device of claim 5 , wherein

when the down signal output from the phase detector is at a high level, the first switch is switched from the closed state to the open state, and the second switch is at the open state.

11. The clock and data recovery device of claim 10 , wherein

since the first capacitor is separated from the transmission line, an RC delay of the data output by the equalizer is reduced compared to a case where both the up signal and the down signal output from the phase detector are at the low levels, so that the phase of the data output from the equalizer and the phase of the clock output from the voltage controlled oscillator are synchronized with each other.