Do we rely too much on simulators?

cmartinez

Joined Jan 17, 2007
8,252
... the hardest part of solving many problems is gaining a firm understanding of what the problem is.
And that's what LTspice has mainly done for me. It has helped me learn specific things by allowing me to tweak individual components so as to more easily visualize how they affect the complete system.

And yes, I've been warned that it has its quirks and limitations. So I take everything it reports with a grain of salt.
 
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AnalogKid

Joined Aug 1, 2013
11,036
I remember reading a science fiction short story set in the future where the character was brought up on heresy charges because he claimed he could do math in his head but everyone knew that only machines could do math.
Heinlein (?) had a story where number and set theory were taught in grade school, and you could do your PhD on long division.

ak
 

Papabravo

Joined Feb 24, 2006
21,225
Ah, I misinterpreted your question. I didn't see a specific post that made a statement about "too much" and so I thought you were throwing out a general question. My apologies.
It was the thread title, and no apology is required since it was a rhetorical question.
 

dannyf

Joined Sep 13, 2015
2,197
The answer depends on the individuals you ask this question of.

I would venture to say that no today's sophisticated ICs are ever pushed into fabrication, let alone production, without having passed verification / validation in a simulation engine.

You have to think simulation as a tool in your tool box. It is stupid not to use a tool when it is helpful, as it is stupid to use a tool to your own detriment.
 

MrAl

Joined Jun 17, 2014
11,457
Hi,

Good question really. Do simulators and more generally computers make us dumber?

I really do hate to quote this, but remember the funny movie, "Stupid is as stupid does".
If you let the simulator make you dumb, it certainly will. A real problem though is that you might not realize it right away because it might seem like a wonder tool at first.

But if you take a deeper look, you'll find that simulators are limited in that it is very hard to prove anything exactly that is of a more general nature. Sure, you can prove that resistor R1 is better at 10k than at 20k, but can you prove that the transition point is at exactly 13487.23894838475849523410082374324242424324234234543591823 Ohms? I dont think so.
Or can you prove that the sensitivity of the output amplitude to a certain resistor value is 12.23 percent per kohm? Maybe, but it takes several trial values to get to that result when you could have done an analysis and come up with a simple V=R*12.23 and thus you would have a formula which solves this quite well.
Also, can you solve for a circuit response regardless of what that value of R might be? Simulators rely on numerical calculations so they can not generalize very well.

They can still give you insight however, if you do a number of experiments with a given circuit, but real mathematics can show you more about a circuit in a much more profound way.

So if you use the simulator for every circuit you ever do you will miss much of the fun and miss the most interesting things about circuits. It's always your decision though. Stupid is as stupid does, so just dont do stupid things :)
 

ronv

Joined Nov 12, 2008
3,770
And that's what LTspice has mainly done for me. It has helped me learn specific things by allowing me to tweak individual components so as to more easily visualize how they affect the complete system.

And yes, I've been warned that it has its quirks and limitations. So I take everything it reports with a grain of salt.
I started out as a trouble shooter, not a designer, so I learned to go fast. I could always turn around and go back without any cost. But when you carry that mentality into design it can make things expensive and slow - order parts, pay for parts, find out parts don't work, etc.. So I always simulate first to eliminate the obvious mistakes while paying attention to voltage, power, and common mode rejection by hand.
 

ramancini8

Joined Jul 18, 2012
473
In general, all ICs are simulated, but not with something as crude as LTSpice. The IC simulators include layout, connection resistance, feedthrough capacitance, etc.
 

cmartinez

Joined Jan 17, 2007
8,252
In general, all ICs are simulated, but not with something as crude as LTSpice. The IC simulators include layout, connection resistance, feedthrough capacitance, etc.
I'm guessing the cost of the die justifies all that prior work... and also, that afterwards thorough testing is done in the real world and compared to the original simulation
 

chuckey

Joined Jun 4, 2007
75
On some forums, people say this circuit does not work as expected on the simulator, can you help me? I regard this as the height of laziness, its seconds to change the layout/component values to try and make it work, yet they don't know enough about electronics to be able to try. They have not got the perseverance or the go, to actually make it work them selves. Will they ever be a success?
In my day, you got out the soldering iron and did it!
Frank
 

dl324

Joined Mar 30, 2015
16,909
I'm guessing the cost of the die justifies all that prior work... and also, that afterwards thorough testing is done in the real world and compared to the original simulation
I worked on microprocessor projects containing hundreds of millions of transistors being designed on a process that was currently being developed. Running multiple types of simulators is still no guarantee that the device will perform as simulated. With a mature process with dozens/hundreds of "tapeouts", simulations can be very accurate.

I don't think the OP was referring to high volume commercial applications where mask sets and production delays can cost hundreds of millions of dollars in lost revenue and near-perfection from hundreds of people is an impossible expectation. Even with simulators, which can't be 100% comprehensive, mistakes will still escape detection.
 

dannyf

Joined Sep 13, 2015
2,197
If you let the simulator make you dumb, it certainly will.
That sounds like the fault of the operator, not the tool the operator is unable to use correctly.

you'll find that simulators are limited in that it is very hard to prove anything exactly
Any approach is going to be limited in one way or another, because no tools can ever be perfect.

And many times, you don't need to be "exact".

Even with simulators, which can't be 100% comprehensive, mistakes will still escape detection.
You cannot be 100% comprehensive any any approach, simulator or not. The fact that a tool (simulator or a human brain, or actual circuit) isn't 100% accurate or comprehensive should be a reason not to use it.
 

dl324

Joined Mar 30, 2015
16,909
You cannot be 100% comprehensive any any approach, simulator or not. The fact that a tool (simulator or a human brain, or actual circuit) isn't 100% accurate or comprehensive should be a reason not to use it.
I don't think that came out the way you intended.

Simulators aren't perfect, but they can be less fallible than people. It depends on the models, algorithms, etc. The problem, as I see it, is when people become excessively dependent on simulators (or anything for that matter). That's assuming that had they been given sufficient resources (time, money, people, etc), they would have had the ability to do it without an aid.
 

dannyf

Joined Sep 13, 2015
2,197
The problem, as I see it, is...
Again, it sounds like the fault of the operator, using a tool incorrectly.

My point is that it is silly to accuse simulators as the root cause of our problems. A simulator cannot make you any smarter, or dumber for that matter, than you already are.

It is a tool that can help you, when used properly, and it is a tool that can hurt you, when used improperly, just like any other tools. It is up to us to understand their limitations and figure out which tools to use for a particular purpose.

We are the ones that use simulators excessively, or insufficiently.

To me, I would rather focus on more value-add things and am perfectly happy to delegate the mundane things to a simulator, because my time is much more valuable than the simulator's.
 
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