[SI-LIST] Re: 1 Gbps on 3.5 mil etch a hazard?
- From: "N. Paul Taddonio" <paul.taddonio@xxxxxxxxxxxxxx>
- To: "Andrew Ingraham" <a.ingraham@xxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Fri, 22 Oct 2010 16:50:59 -0400
Andrew, yes it is crippled. I guess I should look into LT Spice. I found
it impressive recently when I used
it to simulate a variety of LT power supply designs. I haven't used it for
SI sim.
Thanks,
Paul
----- Original Message -----
From: "Andrew Ingraham" <a.ingraham@xxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Friday, October 22, 2010 4:32 PM
Subject: [SI-LIST] Re: 1 Gbps on 3.5 mil etch a hazard?
>> I like to hear about the non linearity etc because I need ammunition to
>> get
>> my employer to spring for the full simulator.
>
> I can't tell you exactly how it would affect your simulation results...
>
> But consider this. ECL outputs tend to have a very low output
> impedance (around 7 ohms) only as long as the emitter follower remains
> on. But if one were to pull the output pin up by only a few tens of
> millivolts, the transistor would turn off and that 7 ohms goes to
> infinity ... well, very large. It won't stay like that continuously,
> except for a few special ECL parts that were designed to 'drive' below
> Vtt, thus allowing their outputs to go open-circuit when low. But it
> could happen on reflections. And then a simplified linear model
> doesn't show what happens at all.
>
> Why can't you use the ECL driver's SPICE model? Is it because it
> would exceed the capabilities of PSpice's demo version? There are
> other free SPICE programs out there (including LTspice) that are not
> crippled. I'm not suggesting they will solve your simulation problems
> thus making commercial software unnecessary; but LTspice (for example)
> is far more capable than the PSpice demo.
>
> But I think you need to pay to get a simulator that understands IBIS.
>
> Regards,
> Andy
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