ALTDQ_DQS2 IP Core User Guide

ID 683742
Date 5/08/2017
Document Table of Contents

DQS Delay Chain

The dqsenable signal grounds the DQS input strobe after the strobe goes to Hi-Z. This is important for bidirectional strobes, where glitches can be filtered effectively through the DQS enable. The dqsbusout signal is the delayed dqsin signal that drives into the dedicated DQS clock network to clock the DQ capture registers so that data is captured at the centre of the eye. The following figure shows a 90° phase shift between the dqsin and dqsbusout signals. This is consistent with the settings in Instantiating the ALTDQ_DQS2 IP Core.

Figure 40. DQS Delay Chain Waveform