Re: [DLL usage Virtex/Spartan-II] HowTo drive CLKDV Div 2 off Chip

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Be carefull. Usually when you instantiate a ibufg, you are actually
instantiating a IOB configured as an input, and a bufg. You only want to use an
IOB as the input and make sure it is loc'd to a clk input pin location.

As for your div/2, you can divide the input to the dll by 2 using the
CLKIN_DIVIDE_BY_2 parameter. Don't know if this helps because the clk0 will be
div/2 since the dll is dividing the input to the dll.





Markus Meng wrote:
 > Hi All,
 >
 > some notes I could not figure out directly from one of the XAPP132, 174
 > from Xilinx. If I want to drive an Off-Chip device with half of the clkin
 > frequency
 > without using a GBUF driver, can I feedback the devided signal from the obuf
 > driving the pin through an IBUFG and still having the DLL functionality of
 > phase
 > shift an duty cycle correction. I read that the feedback signam MUST be
 > clkout
 > or 2xclkout. The problem is that I am running out of GBUF's in my design ...
 >
 > markus
 >



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