Memory device adjusting duty cycle and memory system having the same

1. A memory device comprising:

a clock receiver configured to receive, from a memory controller, a write clock that is used to receive write data during a data write operation;

a duty monitor configured to generate first monitoring information by monitoring a duty of the write clock; and

a duty adjuster configured to adjust the duty of the write clock in response to a duty control signal and output an adjusted write clock,

wherein the memory device provides the first monitoring information to the memory controller, and receives the duty control signal, generated using the first monitoring information, from the memory controller.

2. The memory device of claim 1 , wherein the duty control signal is provided to the duty adjuster, and

wherein the duty adjuster selectively performs a duty adjust operation in response to the duty control signal received from the memory controller.

3. The memory device of claim 1 , wherein the duty monitor is connected to an output terminal of the duty adjuster and is further configured to monitor a duty of the adjusted write clock.

4. The memory device of claim 1 , further comprising a data receiver configured to receive the write data,

wherein

the adjusted write clock is provided to an input terminal of the data receiver, and

the duty monitor is connected to the input terminal of the data receiver and is further configured to monitor a duty of the adjusted write clock that is provided to the data receiver.

5. The memory device of claim 1 , further comprising a mode register set (MRS) configured to store mode register information for a setting operation within the memory device,

wherein the duty monitor is further configured to store the generated first monitoring information in the MRS.

6. The memory device of claim 5 , wherein the duty control signal, received from the memory controller, is stored in the MRS.

7. The memory device of claim 6 , wherein

the memory device further comprises an MRS pin for transferring information that is stored in the MRS or read out from the MRS, and

the memory device communicates with the memory controller to transfer at least one of the first monitoring information and the duty control signal via the MRS pin.

8. The memory device of claim 1 , further comprising:

a read clock generator configured to generate a read clock that is used to output read data during a data read operation, by using the write clock that is output by the clock receiver; and

a read clock duty adjuster configured to adjust a duty of the read clock,

wherein the duty monitor is further configured to further generate second monitoring information about the read clock by monitoring the duty of the read clock.

9. The memory device of claim 8 , further comprising a read clock transmitter configured to transmit the read clock to the memory controller,

wherein the duty monitor is further configured to monitor the duty of the read clock that is provided to an input terminal of the read clock transmitter.

10. The memory device of claim 1 , further comprising:

a plurality of data receivers each configured to receive the write data in synchronization with the write clock; and

a plurality of first duty adjusters arranged in correspondence with the plurality of data receivers,

wherein the duty monitor is further configured to further monitor the duty of the write clock that is provided to at least some of the plurality of data receivers.

11. The memory device of claim 10 , further comprising:

a read clock generator configured to generate a read clock that is used to output read data during a data read operation;

a plurality of data transmitters each configured to output the read data in synchronization with the read clock; and

a plurality of second duty adjusters arranged in correspondence with the plurality of data transmitters,

wherein the duty monitor is further configured to further monitor a duty of the read clock that is provided to at least some of the plurality of data transmitters.

12. A memory device comprising:

a clock receiver configured to receive a clock signal from a memory controller;

a first duty adjuster configured to receive the clock signal from the clock receiver and perform a duty adjustment on the received clock signal;

a clock tree configured to generate one or more write clocks that are used to receive write data, by using the clock signal received from the first duty adjuster;

one or more data receivers each configured to receive the write data in synchronization with each of the one or more write clocks;

one or more second duty adjusters arranged in correspondence with the one or more data receivers and configured to adjust duties of the one or more write clocks that are provided to the one or more data receivers; and

a duty monitor configured to monitor a duty of at least one of the clock signal and the one or more write clocks, and provide first monitoring information, as a result of the monitoring, to the memory controller.

13. The memory device of claim 12 , wherein the memory device receives a duty control signal, based on the first monitoring information, from the memory controller, and

at least one of the first duty adjuster and the one or more second duty adjusters is further configured to perform a duty adjust operation in response to the duty control signal received from the memory controller.

14. The memory device of claim 12 , wherein the duty monitor is further configured to monitor a duty of the clock signal that is output by the first duty adjuster.

15. The memory device of claim 12 , wherein the duty monitor is further configured to monitor duties of the one or more write clocks that are output by the one or more second duty adjusters.

16. The memory device of claim 12 , wherein a duty adjust operation of at least one of the first duty adjuster and the one or more second duty adjusters is enabled or disabled in response to a control command received from the memory controller.

17. A memory system comprising a memory controller, the memory controller comprising:

one or more data transmitters configured to output write data;

a write clock transmitter configured to output a write clock in synchronization with the write data; and

a duty controller configured to receive, from an external source, first monitoring information representing a result of monitoring a duty of the write clock, determine, based on the first monitoring information, whether the write clock provided to the external source has a duty error, and generate a first duty control signal that is used to adjust the duty of the write clock output to the external source.

18. The memory system of claim 17 , further comprising a memory device in communication with the memory controller,

wherein the memory controller is configured to receive the first monitoring information from the memory device, and provide the first duty control signal to the memory device to adjust the duty of the write clock within the memory device.

19. The memory system of claim 18 , wherein

the memory device comprises:

a duty adjuster configured to perform duty adjustment on the write clock received from the memory controller; and

a duty monitor configured to generate the first monitoring information by monitoring the duty of the write clock transmitted to the memory device, and

the duty adjuster is further configured to perform the duty adjustment in response to the first duty control signal received from the memory controller.

20. The memory system of claim 19 , wherein

the memory device further comprises a clock tree configured to generate a read clock that is used to output read data, by using the write clock, and

the duty monitor is further configured to further provide, to the memory controller, second monitoring information generated by monitoring a duty of the read clock.