K and K\  signals in DDR

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    Question: Are K, K\ are differential signals in DDR?



     Please note that K and K\ clocks are not true differential clock signals. There is no differential receiver in the SRAM. The DDR uses the rising edges of K and K\ to latch input signals. Both clocks are single ended signals. Although they are not true differential, it is advised to keep K and K\ 180 degrees out of phase with respect to one another. This effect produces the ability for the DDR to perform a double data rate one clock cycle.

    For more information please refer to the application note QDR (TM)-II and DDR-II Design Guide - AN4065,  which describes the different clocking strategies that can be adopted in QDRII/DDRII SRAMs and it describes each of the strategies in detail.