Fly-By Layout For Multiple DRAM Devices

If you plan to use two or more DRAM devices on your board, Efinix® recommends using a fly-by layout. This method:
  • Avoids T-junctions on the PCB thereby improving the SNR.
  • Reduces the trace lengths between the devices.
  • CK(n-1) trace length must be longer than the DQS(n-1) trace length. n is the number of DDR device used.

If you are only using one DRAM device, a fly-by design is not applicable.

Figure 1. Fly-By Example Layouts