| CPC G11C 11/4076 (2013.01) | 20 Claims | 

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               19. A memory device, comprising: 
            a memory core; 
                a command/address decoder configured to receive a clock signal from a memory controller and to decode a command/address signal received from the memory controller based on the clock signal; 
                a data clock splitter configured to receive a data clock signal of a full rate from the memory controller and to generate four split data clocks by splitting the data clock signal; 
                a reception circuit configured to sequentially output write data received through a plurality of data signals from the memory controller to the memory core in synchronization with the four split data clocks; and 
                a transmission circuit configured to send read data received from the memory core to the memory controller through the plurality of data signals in synchronization with the four split data clocks; and 
                wherein, while the data clock signal of the full rate is being received from the memory controller, the data clock splitter is further configured to perform a synchronization operation on the data clock signal based on a synchronization pattern received through at least one of the plurality of data signals. 
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