[SI-LIST] The Implications of Nonmonotonic Transitions
- From: tucsonAz <tucsonaz111@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Tue, 20 Jan 2009 20:17:20 -0800 (PST)
I have a nonmonotonic transition on a processor¢s data line.
Example:
On a rising edge the signal passes the Vih(min), then back below it, and then
again back above Vih(min). Termination may not be possible due to packaging
constraints and the vendor will most likely only endorse an ideal square wave.
The timing concern is that this ringing from a reflection would push into the
setup time. However, the signal is stable before the required setup time of the
interface, therefore, no impact.
The signal integrity concern is that does this nonmonotonic transition have any
impact to the LVCMOS (not sstl) at the receiving end? Even though the signal is
an acceptable high voltage at the setup time.
I have looked back through my device physics books from school attempting to
find what impacts nonmonotonic transitions present to CMOS with no success. I
have done web searches only finding papers talking about the results on the
timing margin or leading into termination techniques.
Are nonmonotonic transitions acceptable to CMOS outside of setup times? Can
anyone suggest further reading sources?
Your help is appreciated,
Joe Engineer
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