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SKGR0's avatar
SKGR0
Icon for New Contributor rankNew Contributor
6 years ago

How does DDR4-2400 (I/O Clock as 1200MHz) achieve higher data rate of 2.4 GT/s when memory clock is only 300MHz and the data width is limited to 144 bits on an Arria10 device?

3 Replies

  • Deshi_Intel's avatar
    Deshi_Intel
    Icon for Regular Contributor rankRegular Contributor

    Hi,

    DDR4 bandwidth calculation = DDR4 memory clock frequency x 2 x total DQ width

    For instance, using your example

    DDR4 BW = 300MHz x 2 x 144 = 86.4MT/s

    I am not sure how does the 2.4GT/s calculation comes from

    Thanks.

    Regards,

    dlim

    • SKGR0's avatar
      SKGR0
      Icon for New Contributor rankNew Contributor

      Thanks.

      I had found the below details in the Wikipedia Page https://en.wikipedia.org/wiki/Double_data_rate

      DDR4-2400, PC4-19200

      Memory Clock - 300MHz

      I/O Bus Clock - 1200MHz

      Transfer rate - 2.4GT/s

      Theoretical Bandwidth - 19.2GB/s

      How were these numbers derived?

  • Deshi_Intel's avatar
    Deshi_Intel
    Icon for Regular Contributor rankRegular Contributor

    2.4GT/s Transfer rate =1200MHz x 2

    19.2GB/s Theoretical Bandwidth = (1200MHz x 2 x 64 bit DQ) = 153.6Gb/s = 19.2GB/s