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6.4.4.5. Layout Guidelines for DDR3 and DDR4 SDRAM Wide Interface (>72 bits)
The EMIF IP supports up to a 144-bit wide DDR3 interface. You can use discrete components or DIMMs to implement a wide interface (any interface wider than 72 bits). Intel recommends using leveling when you implement a wide interface with DDR3 components.
When you lay out for a wider interface, all rules and constraints discussed in the previous sections still apply. The DQS, DQ, and DM signals are point-to-point, and all the same rules discussed in Design Layout Guidelines apply.
The main challenge for the design of the fly-by network topology for the clock, command, and address signals is to avoid signal integrity issues, and to make sure you route the DQS, DQ, and DM signals with the chosen topology.