Clock and data recovery circuit and a display apparatus having the same
A display device including: a timing controller outputting a reference clock signal and a data packet, wherein the data packet includes a clock signal embedded in a data signal; a clock and data recovery (CDR) circuit receiving the reference clock signal and the data packet; and a display panel displaying an image based on the data packet, wherein, when the CDR circuit receives the reference clock signal, a frequency band of the reference clock signal is detected using a first internal clock signal, a parameter associated with jitter characteristics of the clock and data recovery circuit is adjusted according to the detected frequency band, and a second internal clock signal is output by adjusting a frequency of the first internal clock signal, and when the CDR circuit receives the data packet, the data signal and a clock signal synchronized with the data signal are recovered from the data packet.
1. An operating method of a clock and data recovery circuit, comprising:
receiving a training clock from a timing controller;
detecting a frequency band from the received training clock;
changing at least one parameter of the clock and data recovery circuit corresponding to the frequency band; and
reducing jitter characteristics of at least one clock using the changed at least one parameter.
2. The operating method of claim 1 , wherein the receiving the training clock includes:
receiving a reference clock, which is the training clock, from the timing controller in an initial training mode; and
synchronizing phases of the reference clock and at least one internal clock.
3. The operating method of claim 1 , wherein the detecting the frequency band includes counting a period of the training clock with a clock of a voltage-controlled oscillator.
4. The operating method of claim 1 , wherein the clock and data recovery circuit includes a charge pump, a loop filter and a voltage-controlled oscillator,
wherein the at least one parameter includes a parameter of each of the charge pump, the loop filter and the voltage-controlled oscillator.
5. The operating method of claim 4 , wherein the at least one parameter includes a current output by the charge pump, a resistance or a capacitance of the loop filter, or a gain of the voltage-controlled oscillator.
6. The operating method of claim 4 , wherein the method further includes:
performing coarse tuning of the at least one clock using the frequency band.
7. The operating method of claim 6 , wherein the method further includes performing fine tuning of the at least one clock using a control code,
wherein the control code, as determined by an automatic frequency controller, corresponds to a difference between a frequency of the training clock and a frequency of the at least one clock.
8. The operating method of claim 1 , wherein the clock and data recovery circuit is used for a high speed operation region.
9. The operating method of claim 8 , wherein the jitter is maintained in a low speed operation region.
10. The operating method of claim 1 , further comprising receiving data packet having a wide range of frequencies from the timing controller in a normal operating mode.
11. An operating method of a display driving integrated circuit, comprising:
receiving a reference clock from a timing controller in an initial training mode;
synchronizing phases of an internal clock and the reference clock in the initial training mode;
receiving a data packet from the timing controller in a normal operating mode;
recovering a data signal and clock signal synchronized with the data packet in the normal operating mode,
wherein the synchronizing the phases includes:
detecting a frequency band of the reference clock using the internal clock; and
adjusting at least one parameter of a Clock and Data Recovery (CDR) circuit according to the frequency band.
12. The operating method of claim 11 , wherein the synchronizing the phases further includes tuning a frequency in a voltage-controlled oscillator of the CDR circuit.
13. The operating method of claim 11 , wherein the method further includes: performing coarse tuning to the frequency band of the reference clock in a loop filter of the CDR circuit.
14. The operating method of claim 11 , wherein the method further includes:
generating a control code using an automatic frequency controller wherein the control code corresponds to a difference between a frequency of the reference clock and a frequency of the internal clock; and
performing fine tuning using the control code to adjust the frequency band of the reference clock in a voltage-controlled oscillator of the CDR circuit.
15. The operating method of claim 11 , wherein the method further includes: adjusting a current parameter according to the frequency band in a charge pump of the CDR circuit.
16. An operating method of a display device, comprising:
receiving a data packet at a display driving integrated circuit, wherein the data packet is provided from a timing controller;
recovering a data signal and a clock signal synchronized with the data packet in a Clock and Data Recovery (CDR) circuit of the display driving integrated circuit; and
displaying the data signal on a display panel,
wherein the CDR circuit detects a frequency band of a reference clock using an initial clock, and adjusts at least one parameter of the CDR circuit according to the frequency band.
17. The operating method of claim 16 , wherein the CDR circuit is configured to process data in a high speed operation region and reduce jitter of the clock signal in a low speed operation region.
18. The operating method of claim 16 , wherein the at least one parameter includes a current output by a charge pump, a resistance or a capacitance of a loop filter, or a gain of a voltage-controlled oscillator.
19. The operation method of claim 18 , wherein the CDR circuit performs coarse tuning to the frequency band of the reference clock in the loop filter.
20. The operation method of claim 19 , wherein an automatic frequency controller generates a control code corresponding to a difference between a frequency of the reference clock and a frequency of the clock signal, and performs fine tuning using the control code to adjust the frequency band of the reference clock in the voltage-controlled oscillator.