External Memory Interface Handbook Volume 2: Design Guidelines

Download
ID 683385
Date 5/08/2017
Public
Document Table of Contents

10.7.1.2.1. Skew

Ensure that all clocked signals, commands, addresses, and control signals arrive at the memory inputs at the same time.

Trace length variations cause data valid window variations between the signals, reducing margin. For example, DDR2-800 at 400 MHz has a data valid window that is smaller than 1,250 ps. Trace length skew or crosstalk can reduce this data valid window further, making it difficult to design a reliably operating memory interface. Ensure that the skew figure previously entered into the Intel® FPGA IP matches that actually achieved on the PCB, otherwise Quartus Prime timing analysis of the interface is accurate.

Did you find the information on this page useful?

Characters remaining:

Feedback Message