Visible to Intel only — GUID: sam1403478462891
Ixiasoft
Visible to Intel only — GUID: sam1403478462891
Ixiasoft
7.3.3.1. Delay-Locked Loop
The DQS phase-shift circuitry uses a delay-locked loop (DLL) to dynamically control the clock delay required by the DQS/CQ and CQn pin.
The DLL uses a frequency reference to dynamically generate control signals for the delay chains in each of the DQS/CQ and CQn pins, allowing the delay to compensate for process, voltage, and temperature (PVT) variations. The DQS delay settings are gray-coded to reduce jitter if the DLL updates the settings.
There are a maximum of four DLLs, located in each corner of the Stratix® V devices. You can clock each DLL using different frequencies. Each DLL can have two outputs with different phase offsets, which allows one Stratix® V device to have eight different DLL phase shift settings.
You can have two different interfaces with the same frequency sharing a DLL, where the DLL controls the DQS delay settings for both interfaces.
Each I/O bank is accessible by two DLLs, giving more flexibility to create multiple frequencies and multiple-type interfaces. Each bank can use settings from one or both adjacent DLLs. For example, DQS1T can get its phase-shift settings from DLL_TR, while DQS2T can get its phase-shift settings from DLL_TL.
The reference clock for each DLL may come from the PLL output clocks or clock input pins.