new spice

It'll be interesting to try out, if "Currently working on an appropriate business model for it" doesn't involve too much dough or intrusive license terms.

I wonder if he's put in any support for building models?

Cheers

Phil Hobbs

The various flavours of Spice all support a variety of models, which tend to be supplied by the people who make the devices.

Manufacturer's Spice models tend to be less than wonderful. The late Jim Thompson made a business of being able to produce more useful models.

Kevin Aylward might be another source. His SuperSpice worked fine for me.

Ever tried Micro-Cap? It is no longer maintained, but free as in beer.

I used Micro-Cap in the lat 1990s and then LT-spice.

MicroCap worked well too. Of course, I downloaded it when it was offered for free recently.

Supposedly, Mike's new version will try to design or parially design you circuit after giving it the curves. I would imagine it could, for instance, fill in the parts values for an active filter by drawing a response curve. I have seen DSP software do this for digital filters.

boB

Being free had more to do with its popularity than anything else.

I had a copy of Micro-Cap V back in the Win 98 days iirc. Worked okay.

Maybe Micro-Cap would have better luck making some of TI's crappy op amp models converge. (I'm looking at you, OPA140!)

Cheers

Phil Hobbs

TINA could have something to do with it.

I could imagine some improvements:

1 Harmonic balance 2 nonlinear noise for example: noise of a chopper amplifier. it has no steady state requires (1) 3 easy S-parameters 4 built-in loop gain probes 5 multiple simulations without having to comment/uncomment .tran .ac .noise instructions.

Some other proposals would require mechanical layout, that is probably asking too much.

This is still a far cry from Keysight ADS, money & performancewise.

But to make someone spend money for this at all, the advantages would have to be substantial. There are a lot of roadkills among the Spice workalikes.

Gerhard

Am 29.09.21 um 18:15 schrieb boB:

Probably like the intelligent parts in ADS. You just draw a filter and in its control page you say what you want: passive LC, op amp, sampled, frequencies, stripline, microstrip in its diverse variants and it is completed up to the layout of your hairpin filter on, say, Rogers 4003, ready for EM simulation.

Gerhard

...but why ......?

-- Kevin Aylward

SuperSpice

Maybe he enjoys it. I'm sure he's enormously wealthy and could do anything he wahts.

I want a Spice that uses an nvidia board to speed it up 1000:1.

Am 30.09.21 um 21:24 schrieb John Larkin:

Hopeless. That has already been tried in IBM AT times with these Weitek coprocessors and NS 32032 processor boards; it never lived up to the expectations.

That's no wonder. When in time domain integration the next result depends on the current value and maybe a few in the past, you cannot compute more future timesteps in parallel. Maybe some speculative versions in parallel and then selecting the best. But that is no work for 1000 processors.

The inversion of the nodal matrix might use some improvement since it is NP complete, like almost everything that is interesting. Its size grows with the number of nodes and the matrix is sparse since most nodes have no interaction. Dividing the circuit into subcircuits, solving these separately and combining the results could provide a speedup, for problems with many nodes. That would be a MAJOR change.

Spice has not made much progress since Berkeley is no longer involved. Some people make some local improvements and when they lose interest after 15 years their improvements die. There is no one to integrate that stuff in one open official version. Maybe NGspice comes closest.

Keysight ADS has on option to run it on a bunch of workstations but that helps probably most for electromagnetics which has not much in common with spice.

Cheers, Gerhard

I think a factor of two *overall* is possible with a bit of work. I've seen proposals that suggest a factor of 4 is likely the upper limit on any such work. Some models may hit sweet spots -- but not the sort of thing you're going to boast about in sales literature!

These are small enough that it's easier just to twiddle your thumbs and wait for next year's PC update cycle to get that improvement "for free" (i.e., for no development work cuz new work means new bugs).

A big part of the problem is folks want these tools for free. That attitude suggests they place no value on the time they save running simulations (or, that their time *has* no value).

Someone will come up with a breakthrough and sell it as a *service*. So, you'll submit your circuit and get a bill for the analysis. Of course, this will likely cut down on the "what if" use of such a tool (cuz changing a portion of the circuit will still require a complete REanalysis... likely hard to leverage any prior computations to reduce the cost of those efforts)

Then again, software-as-a-service is the obvious future.

You are probably right here.

No. The big part of the problem is that spice 2g4 or 3.x was always free and some people added some miniscule things like a GUI and expected they would rule the world from now on since THEY had written THE simulation program. For a time that worked for few of them, like pspice that got swallowed by Orcad that got swallowed by Cadunz. And where are they now? When have you seen the last result from pspice and its offspring?

JT from s.e.d. is RIP now for some years, but do you think he missed any of the new developments? No, not really. Which new developments?

You mean, like H-Spice some decades ago? OMG, I'm growing old. Some customers of mine don't like it when I have their stuff on MY computer, much less in a cloud.

Cheers, Gerhard

On 2021-10-01 05:47, Don Y wrote: [...]

I'll be kicking and screaming the whole way.

Jeroen Belleman

Just say "no"!

What you have *today*, works. Keep that in mind for tomorrow... and the day after... and...

(Do you really *need* version N+m of whatever tool is working for you *now*?)

Hah, this is certainly true on many occasions - though not universal of course. I myself must have done so at times when I have just needed some result and move on (who has not done it, that is, we all use calculators etc.). There are times when I have used FP because it has been the only way to get out of the silicon what I needed (e.g. DSP-ing on a 32 bit machine with a 64 bit FPU). And then there can come the moment when you just have to trade off accuracy for dynamic range, which is when you do need FP and you do understand the problem :-).

I remember that. I don't think that many telescope controller computers possessed FP hardware, and software library implementation was too slow.

But at least in my world, we went to floating-point ASAP because it greatly reduced the programming effort, and finding and fixing bugs due to scaling errors. Having big enough computer words helped a lot too, but the key was when FP arithmetic was roughly as fast as integer hardware, or at least fast enough for the task at hand.

War story: My best-selling memo in the early 1980s documented a crank-and-grind procedure to convert a math formula into the equivalent scaled binary. The CPUs were 68000-family. Before, people couldn't figure out when to multiply and when to divide.

Joe Gwinn

Describing the matrix as sparse ignores the potential advantages of the topology. A matrix allows anything to connect to anything with equal cost, but in actual circuits, connections are far more likely to be to "nearby" components - where nearby means there is another short path to the same component.

JIT FPGA synthesis could use that property to make use of local interconnect instead of needing an escalating amount of scarce global interconnect.

CH