Answers Database
Virtex XAPP132: CLKDLL Jitter Spec in App. note 132 is not clear
Record #4935
Product Family: Hardware
Product Line: Virtex
Product Part: Virtex General Hardware
Problem Title:
Virtex XAPP132: CLKDLL Jitter Spec in App. note 132 is not clear
Problem Description:
Urgency: Standard
General Description:
Page 14 of the Xilinx Appnote 132 refers to 50 pico seconds of
Jitter. Yet the Figure at the bottom of page 14 makes it
unclear if it is a total of 50 picoseconds of jitter, or
+/- 50 picoseconds of jitter.
Solution 1:
The way to interpret the jitter specifications is that the output of the dll will have
a jitter of +/-100 more than what the input is.
For example. If your input jitter is +/-50, then the output jitter of the
DLL will be +/-150
Solution 2:
The maximum input jitter spec for low frequency is 300ps, and for high
frequency is 150ps for the CLKDLL input. The application note indicates
that the maximum jitter is 50ps. This is a misprint. 50ps is from
a testcase, but not the actual maximum spec.
End of Record #4935 - Last Modified: 08/30/99 10:35 |
