[DLL Virtex/Spartan-II] Which is the right feedback in x1 an

[Markus Meng]

Hi All,

I discovered that I use in my working application the x2 Clock Output
as the feedback - after the GBUF - for a DLL that deskews a 48Mhz
input clocks and provides to output clocks for internal usage.

Is this wrong, I am not shure anymore, however I read in XAPP132
and XAPP174 that you have to use x1 output signal - after the GBUF -
if you want to to make use of an internal x1 and x2 clock that
are in phase, controlled by one DLL...

A short note would help

markus


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[John]

The DLL can handle either a 1x or 2x clk as it's feedback. It just can't use the
fx or phase offset ouputs as the feedback

Markus Meng wrote:

Hi All,

I discovered that I use in my working application the x2 Clock Output
as the feedback - after the GBUF - for a DLL that deskews a 48Mhz
input clocks and provides to output clocks for internal usage.

Is this wrong, I am not shure anymore, however I read in XAPP132
and XAPP174 that you have to use x1 output signal - after the GBUF -
if you want to to make use of an internal x1 and x2 clock that
are in phase, controlled by one DLL...

A short note would help

markus