Re: FW: FW: Spice Model of IBIS

Jon,

Well said! I agree, let's use the right tools for the job.
All are appropriate within specific contexts. And lets not
forget the comfort factor. Once one becomes familiar with
a specific tool that does a given job, it is hard to overcome
the inertia and change to a tool that might be different, if
not better.

You're right. If the pcb tolerance is +/- 10% and the part process
tolerance is +/- 30%, simulator differences are generally
inconsequential.

I and my customers value my time. For my time, I generally choose
a tool based upon ease of use, speed, and accuracy. In that order.

Scott McMorrow
SiQual

Jon Powell wrote:

> Well, I just couldn't resist.
>
> I certainly wouldn't argue with anyone that SPICE (actually some SPICE
> commercial derivative) is the premier circuit simulation technology that
> is currently publically available. I also wouldn't argue with anyone who
> said that IBIS has some problems that need to be addressed.
>
> However, the market has shown that there is a need for a PCB SI
> simulation technology that offers features that transcend the current
> SPICE node based syntax. Think of the bigger problem. You need to
> simulate the SI and Crosstalk effects of every net on a PCB. You need
> MIN MAX timing from every driver to every receiver. You need SI and
> Noise margin numbers for every net. And you need them quickly enough so
> that you can use the data to turn the design a couple of times. I
> believe these issues are difficult to solve using SPICE as it (they)
> exists on the market today.
>
> Of course, I use SPICE every day. I think it is great. I just believe in
> using the right tool for the right job and I have more than one job to
> do.
>
> Here is a conceptual example:
> you have a 32 wire bus. Each wire couples to it's neighbors. You need to
> simulate every wire and the effects on that wire by it's immediate
> neighbors. You do not want to waste simulation time by simulating
> effects of the wires that are more than a couple of conductors away.
>
> How would you solve this problem using SPICE?
> Can it be solved automatically?
> How would spice represent the names of the different nets? (ie. what is
> the crosstalk on D13?).
>
> As for accuracy:
> Leave the argument of which approach is more accurate for the moment.
> what is the accuracy of your inputs? (PCB stack-up, SPICE model data,
> Dielectric constant, trace width).
> If you are simulating to a higher accuracy than your data inputs then
> you are wasting time and deceiving yourself. I think that a teacher told
> me this in 5th grade but I never really believed it until I started
> doing SI simulation.
Received on Tue Mar 31 10:07:50 1998