[SI-LIST] Eye diagram and port definition in IBIS
- From: "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Thu, 14 Apr 2005 14:29:55 -0700
Gary,
Regarding your question at the end, I looked over the IBIS spec,
and found that there is no definition in the spec for what a port
is. From the writing it appears that the author(s) had electrical
connectivity in mind (voltages and currents), because "digital port"
and "analog port" is all over the spec. However, in a broader
sense, we could think about digital and analog as discrete or
continuous, and as such they could refer to anything, such as
fluidic, thermal, mechanical, etc..., not just electrical.
So the IBIS spec needs a clarification to define this better. As it
stands, someone could write an [External Circuit] with mechanical
ports to model the mechanical interactions between speakers and
the electronics, or model heat sinks through thermal ports... etc.
So according to the letter of the law it is not prohibited, but I
don't think it was intended either. It better be defined,
otherwise we may be in for a surprise down the line...
Arpad
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of Pratt, Gary
Sent: Thursday, April 14, 2005 8:49 AM
To: twesterh@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Eye diagram measurement - And leaves your teeth =
Shiny White Too!
Yes Todd. You are correct. The results are the difference between the
earliest and latest zero-crossing observed up to that point in time, so
the plot appears to be an exponential-like rising curve approaching an
asymptote. (One of our smarter list members would need to comment if it
might be valid to extrapolate this curve to determine the worst case
jitter of after infinite time.) Would be easy to make it non-cumulative
and calculate an RMS value, or take an FFT and look at the spectral
content, or whatever. Flexibility is the beauty of AMS.
And yes, the scale factor is 1mv/ps. Though, now that you mention it,
I'm not sure if IBIS 4.1 is limited to voltages. I know the AMS
language (and the simulator) would be perfectly happy to output and
display units of time directly. Might be something interesting to
investigate.
Gary
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