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Re: Circuit simulation software


Use-The-Envelope-Icon@My-Web-Site.com says...
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Wasn't available in ~'76. ;-)

--
  Keith

Re: Circuit simulation software


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well, I have recently used verliloga models supplied by cadence, and
they have offsets, slews etc all parametized. You need to set them of
course!

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And more importantly, how to correct/set them up so that they can be
trusted.


Kevin Aylward B.Sc.
snipped-for-privacy@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"



Re: Circuit simulation software


On Thu, 22 Jun 2006 18:35:24 GMT, "Kevin Aylward"

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Reminds me, I need to add offset to my Configurable OpAmp model.  I
already have slew rate, GBW and excess phase modeled.

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Yep!

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Agreed ;-)

                                        ...Jim Thompson
--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Re: Circuit simulation software


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Yes.

The issue with the novices in here, is that they make all these daft
claims that spice isn't up to the job, when the reality is that they are
not up to the job of using Spice.

Its like claiming a PhD math expert shouldn't be using MathCAD, or a
carpenter shouldn't be using a power drill etc. One has to learn how to
use the tools of the trade *correctly*. This can take many years for
some.

Kevin Aylward B.Sc.
snipped-for-privacy@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"



Re: Circuit simulation software


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That's only if one is too inexperienced to know how to use models that
address 1st order errors.

Of course if people are clueless its GIGO. However, people that
correctly understand analogue and the simulater, simulation is trully
wonderfull. No one is suggesting driving a simulater in ignorance. As I
have already mentioned, the only way to gain a true genuine
*understanding* of the physics of colliding black holes is to use
simulation programs. The equations are just too complicated to "see"
what they mean without doing *experimental* simulations, and this is
done by people with PhDs and 20 years direct experience. Its just the
way it is. Most modern technology is way too complicated to understand
by pen and paper anymore, no matter how much we delude ourselves. Sure,
we all like to imagine that we are Steven Hawking doing grand
calculations in our head, but even he cant actually get the answers
without running simulations.


Kevin Aylward B.Sc.
snipped-for-privacy@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"



Re: Circuit simulation software



John Larkin wrote:
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I think only for some modern programmers ... many of us learned to
design software when you might get a few test runs a week on batch
systems.

Others only get one shot at a production run ... aerospace guys for one
... and a lot of others, where you reall do have to have your software
right first time.

There are an equally sloppy number of FPGA/CPLD HW guys these days.


Re: Circuit simulation software



John Larkin wrote:
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AHMEN :))


Re: Circuit simulation software


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No, you didnt design it then, you just copied (replicated) something
else you already knew worked. The *only* way to know if something
actually works, is to measure if it works. Even then you could be
fooled.


Kevin Aylward B.Sc.
snipped-for-privacy@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"



Re: Circuit simulation software


On Thu, 22 Jun 2006 18:36:33 GMT, "Kevin Aylward"

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Are you actually incapable of designing an original circuit that you
are confident will work? I do that all the time. I dislike copying
circuits, even my own. Sometimes I do a little math, sometimes even
use a calculator, and sometimes sketch a Bode plot or such to check
closed-loop stability. Simulation is reserved for just the rare,
really hardcore cases.

Of course it gets tested after Production builds the first, sellable
article, but all that simulation/breadboarding time was sliced out of
the critical path.


John



Re: Circuit simulation software


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As I have explained many times. The only way to achieve something truly
new is for that newness to be achieved by randomness. If it is random,
by definition, it operation can not be predicted with certainty.

Of course, I have designed many circuits that are "novel" by combining
existing circuits (cross coupled genes) that have worked 1st time. In
these case one can make a prediction based on existing knowledge.


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You still dont get the point. Its strickly imposible to design a "new"
circuit without copying something. Again, I have already explained, that
one must use *existing* knowledge (i.e. copying) to produce a usefull
design, for example, one will use diff pairs, current mirrors, cascodes,
push-pull outputs, salen-key filter, etc.

To obtain a totally original circuit you must use a pifetz, connected to
wizbangs, driven by gottenburgs, and you no can't connect them up with
wire, thats already been done, so not orginal.

Tell, when and how did you manage to invent these new physics
components?

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You are not doing complex analogue designs then. Its that simple.

I think you are not being honest with yourself, or simply not
understanding what it is you actually do or what I am saying.


Kevin Aylward B.Sc.
snipped-for-privacy@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"



Re: Circuit simulation software


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Geeze Kev, have you ever considered a career in Law? Aside from the
obvious issue with dailysex, you have the required pedanticism in spades :)

Cheers
Terry

Re: Circuit simulation software



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"required pedanticism in spades"?  ROTFLMAO!  Can I "pinch" that ?:-)

                                        ...Jim Thompson
--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Re: Circuit simulation software


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Please do. I seriously considered a career as a wordsmith, but
electronics was far more interesting. I consider it an unfair trade,
given what I have learned from you :)

Cheers
Terry

Re: Circuit simulation software



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Thanks ;-)

                                        ...Jim Thompson
--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
We've slightly trimmed the long signature. Click to see the full one.
Re: Circuit simulation software


On Fri, 23 Jun 2006 17:30:47 GMT, "Kevin Aylward"

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Whether a circuit's discovery is random or divinely inspired or
whatever, the predictability of its behavior can be evaluated
independent of its origin. Randomness is not a permanent pollutant.

Or are you saying that you only trust and use circuits that someone
else has already used and proven to be reliable?

John



Re: Circuit simulation software


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The *only* way to be 100% sure of a prediction is actual measurement
after the fact.

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You stll aint listening John. You are looking at this from too low a
level.


Kevin Aylward B.Sc.
snipped-for-privacy@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"



Re: Circuit simulation software


On Sat, 24 Jun 2006 06:50:41 GMT, "Kevin Aylward"

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Sure. But I can test a production first-article, and production can
test every unit before they ship. If I have a high enough confidence
that a design will work, it's an expensive waste of time to breadboard
or simulate. It's ideal to go from design directly to a sellable PC
board. You've got to lay out and assemble and test the board
eventually, so you may as well do it now. The skill is in properly
calibrating the risk.

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The level I'm looking at this from is the bank balance, which seems
pretty high-level to me.

John



Re: Circuit simulation software


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Ahmmmm.. Well we are coming totally opposite directions. There is no
f^%$ing chance that typical analogue i.c designs can be produced,
without extensive simulation. The cost of simulation compared to mask
costs and 3 month waits until it comes back from the fab is a risk *NO*
semiconductor company will make. Ever. Indeed, it can be a sacking if
you ship the tape without doing WC/MC.


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And one never taken today, with ic design.

Kevin Aylward B.Sc.
snipped-for-privacy@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"



Re: Circuit simulation software


On Sat, 24 Jun 2006 16:45:37 GMT, "Kevin Aylward"


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I'm putting parts on boards, and you're baking silicon, so things are
a bit different. I can sell, say, 95% or more of my original board
layouts, given the option to change values and maybe add a discreet
kluge. And spinning a board takes as little as a week or two, and
costs a couple thousand dollars. Each of us, ideally, applies the
optimum amount of pre-fab verification to maximize payout, and neither
of us can sensibly keep testing and simulating to get to 99.99%
confidence; at some point we have to say "enough" and fab the damned
thing.

But I still think that a lot of people fling out their "designs" too
fast and then simulate too much. I encourage my engineers, and myself,
to get it right by design and spend less, typically zero, time
simulating and breadboarding, and that becomes a habit and a
discipline that pays off in time and quality.

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Do you run at exactly zero risk? 100% of first silicon is always
right?

John



Re: Circuit simulation software


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This depends on your definition of "design". For me design *is* running
appropiate simulations. Of course, running simulations blind is not
"design", and I am not suggesting that.

For example, suppose I wanted to set the Vgs voltage on a mosfet
connected diode. Do I know what the formulas are inside out? Sure I do.
Do I bother to look up the spice data for K and calculate the value?
Nope. Its far quicker for me to run a few sims from an initial guess
from experience of knowing the approx Vgs for a given current. I know
what the sensitivities are so I know what things I can wing it with. I
don't even calculate 7*9 by hand.

My pen and paper is the GUI schematic. Its just far quicker to try out
new connections in the virtual world.

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I was referring to the risk of not simulating at all. Of course there is
a risk, and many chips end up with several spins before its gotten
right. IC Companies usually have a *mandatory* simulation sign off
sheet.

Kevin Aylward B.Sc.
snipped-for-privacy@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

"There are none more ignorant and useless,than they that seek answers
on their knees, with their eyes closed"



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