[SI-LIST] ppm related question
- From: "Anand Srinivasan" <sanand@xxxxxxxxxxxx>
- To: Si-list@xxxxxxxxxxxxx
- Date: Tue, 15 Apr 2008 21:09:19 -0700
Hi All,
I have an IXIA packet generator/analyzer providing ethernet data streams
to my switch. I am finding that the switch is receiving data at a rate
that is slightly higher than the rate at which switch is transmitting
data. I attribute this to some clock ppm variations in the switch. I
have some questions related to the ppm variation in clocks:
1. If i have a clock of X MHz and if i feed this clock to a pll to get
a clock of freq Y Mhz, will the ppm variation of the clocks X and Y
remain the same?
2. When we state that there is a +100 ppm variation from X MHz in the
clock, does this mean that the clock now is a constant frequency of (X
MHz + 100ppm)? or does it dynamically vary between X MHz and (X MHz +
100ppm)?
3. Would signal integrities issues on the board affect ppm variations in
clocks?
4. Is there any on-board correction methodologies that can be applied to
adjust the ppm variations in clocks?
Thanks,
Anand
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