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DDR to processor interface

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  • DDR to processor interface

    I wanted to learn the design of DDR3 or DDR4 memory to processor interfacing. So, my question is how to fix the value of length tuning and where is the option in altium designer to put this value? If I have the rise time of the signal, how can I calculate the length tuning from there? And what parameters will be needed for this length matching?​ Please, give me an example of it.
    Last edited by Shahriar sakib; 03-03-2023, 06:41 AM.

  • #2
    Here's one of robertferanec's videos about DDR2 and DDR3 that should get you going. This should help you understand how to use the length tuning aspects of Altium and perhaps you can apply to anything as desired? This video explains one of possible techniques used for DDR2 / DDR3 length matching in Altium Designer.


    • #3
      If the signal rise time is 1ns then what should be the actual length of the signal trace for length tuning?


      • #4
        length should be less than 3inch.


        • #5
          search for design guides of well known processors e.g imx6 (DDR3) or imx8 (DDR4) and you can use these as a starting point to answer your questions. But generally, when you select a processor for your project, it's manufacturer should have a design guide with recommendations. These recommendations may be different between different chips - so there are no generic rules for every ddr3 or ddr4 layouts.

          If you are not sure, you can do length matching within 10 mils. That will work for most interfaces.