All,
Radek raises an interesting question and this is related to the LTI
requirement / assumption in IBIS-AMI.
If the analog front end of the buffer is a power aware model, the
fluctuations on the power lines will modulate the buffer's drive
characteristics. This is a time varying behavior, which we can't have
according to the LTI requirement.
If this time variance is short lived and caused by the same buffer
which is involved in the AMI analysis, it could be captured in a step
response, which is one way of generating the channel impulse
response for the AMI models. But long term variations, extending
beyond a step response will not be captured this way. Also power
variations due to other effects on the die, such as SSO caused by
other buffers can't be captured this way, because they are more
random in nature.
Another complication is that BIRD158 models may not be used in
channel characterizations using a time domain step response. I
don't know how power effects could be included if the analysis is
done in the frequency domain.
So the short answer in my mind is that for AMI simulations we should
not attempt to include power delivery effects. But this seems to be
a model maker problem, not a spec problem. Just because the spec
allows you to do it, it doesn't mean that you have to do it.
Thanks,
Arpad
========================================================
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] ;
On Behalf Of Walter Katz
Sent: Tuesday, August 29, 2017 12:58 PM
To: ibis-interconn@xxxxxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: [ibis-interconn] reconciling BIRDs 158 and 189
Radek,
What specific question relevant to power supply terminals of BIRD 189.x models?
The only possible relevant question is what node in my simulation deck needs to
be hooked up to the reference terminal of the Ts4file. Since BIRD 158
represents differential s-parameters, this reference voltage is only important
in power aware simulations, and in that case should use the reference node of
the I/O buffer it is connected to. This reference node is the buffer rail
terminal whose value of [Pulldown Reference], [GND Clamp Reference], [Pullup
Reference], [Power Clamp Reference] is zero.
Walter
Walter Katz
wkatz@xxxxxxxxxx<mailto:wkatz@xxxxxxxxxx>
Phone 303.449-2308
Mobile 303.335-6156
From:
ibis-interconn-bounce@xxxxxxxxxxxxx<mailto:ibis-interconn-bounce@xxxxxxxxxxxxx>
[mailto:ibis-interconn-bounce@xxxxxxxxxxxxx] On Behalf Of ;
radek_biernacki@xxxxxxxxxxxx<mailto:radek_biernacki@xxxxxxxxxxxx>
Sent: Tuesday, August 29, 2017 1:36 PM
To: ibis-interconn@xxxxxxxxxxxxx<mailto:ibis-interconn@xxxxxxxxxxxxx>;
ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: [ibis-interconn] reconciling BIRDs 158 and 189
Hi All,
With the coming interconnect/package modeling via BIRD 189.x and the specific
package modeling needs of BIRD 158.x I have a question. Do we need to provide
specific guidance, or even restrict BIRD 189.x generality of the package
modeling for the needs of BIRD 158.x? In particular, the question is how the
general interconnect/package model of BIRD 189.x is to be hooked up to the
schematic of BIRD 158.x. Specifically, the question is relevant to power supply
terminals of BIRD 189.x models.
Radek
