[SI-LIST] Eye diagram and port definition in IBIS
- From: "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Thu, 14 Apr 2005 19:07:34 -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
--------------------------------------------------------------------
-----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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