Wanted: LM-709 (Spice model) National Op-Amp

[Jim Thompson]

On Mon, 19 Sep 2005 03:55:07 GMT, "Robert" <Robert@yahoo.com> wrote:

"Jim Thompson" <thegreatone@example.com> wrote in message
news:aksri1p5jplv8n72iioc2qqauvbvgi0fiu@4ax.com...
On Sun, 18 Sep 2005 21:02:25 GMT, "Robert" <Robert@yahoo.com> wrote:

[snip]

Two passive components, a resistor and a cap, left in a netlist connected
to ground WITH the other end disconnected causes a circuit to converge
when
without them it does not. Bob went on to say (tongue in cheek?) that
perhaps
non-functioning components strewn randomly through a design could be an
add
on Spice convergence feature.

Though Bob Pease is a fellow classmate of mine at MIT, he is very
often quite full of it... a good portion of what he propounds is just
plain urban legend BS.

Sure. But I don't think he got such simple details wrong. And I don't think
he was just making up a story. Possible, but not likely.

The way he typically spouts I often wonder if he's ever used Spice at
all.


That does not have anything to do with the type of errors you mentioned.
And
the existence of such a problem points to deeper problems with Spice than
you mention.

A good simulator will report floating nodes.

Who said he had a good simulator? I imagine it was a company version of
Spice from back in the days when they were still working the kinks out. If
you want I can dig up the reference from my old copy of his book.

Robert

He castigates Spice to this very day. When we were fellow students at
MIT he was a wee bit kooky (charging up flights of stairs like Teddy
Roosevelt in "Arsenic and Old Lace")... and he's still kooky.

Have you been to one of his "seminars"? I went to one last year that
was here in Phoenix, just to say "Hi". Technical content zero, funny
marketing presentation, yes.

His columns seem to have virtually no technical comment anymore, just
what vitamins he's taking, and how long he can go without taking a
leak ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Chuck Harris]

Jim Thompson wrote:

He castigates Spice to this very day. When we were fellow students at
MIT he was a wee bit kooky (charging up flights of stairs like Teddy
Roosevelt in "Arsenic and Old Lace")... and he's still kooky.

Might it be that he liked the exercise (an unusual thing for a toolie to
to be sure)? I generally take stairs over elevators, or escalators, and
park in the distant spots in parking lots... Does that make me kooky?..
or perhaps just someone who searches for exercise where he can find it?

Now, if he sings marching songs, at the top of his lungs, as he mounts
the stairs, that would be kooky!

Have you been to one of his "seminars"? I went to one last year that
was here in Phoenix, just to say "Hi". Technical content zero, funny
marketing presentation, yes.

His columns seem to have virtually no technical comment anymore, just
what vitamins he's taking, and how long he can go without taking a
leak ;-)

Hmmm? Sounds thematically similar to some of your postings about
your colon, and stuff ;-)

-Chuck

 

[Jim Thompson]

On Mon, 19 Sep 2005 11:39:28 -0400, Chuck Harris
<cf-NO-SPAM-harris@erols.com> wrote:

Jim Thompson wrote:


He castigates Spice to this very day. When we were fellow students at
MIT he was a wee bit kooky (charging up flights of stairs like Teddy
Roosevelt in "Arsenic and Old Lace")... and he's still kooky.

Might it be that he liked the exercise (an unusual thing for a toolie to
to be sure)? I generally take stairs over elevators, or escalators, and
park in the distant spots in parking lots... Does that make me kooky?..
or perhaps just someone who searches for exercise where he can find it?

I used to do that, now I'm into Post Polio Syndrome :-(

Now, if he sings marching songs, at the top of his lungs, as he mounts
the stairs, that would be kooky!

I don't remember if he screamed anything or not, but he sure drew a
lot of attention, all dressed out in lederhosen and roaring up the
stairs.

Have you been to one of his "seminars"? I went to one last year that
was here in Phoenix, just to say "Hi". Technical content zero, funny
marketing presentation, yes.

His columns seem to have virtually no technical comment anymore, just
what vitamins he's taking, and how long he can go without taking a
leak ;-)

Hmmm? Sounds thematically similar to some of your postings about
your colon, and stuff ;-)

-Chuck

I don't get paid :-(

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Chuck Harris]

Jim Thompson wrote:

Might it be that he liked the exercise (an unusual thing for a toolie to
to be sure)? I generally take stairs over elevators, or escalators, and
park in the distant spots in parking lots... Does that make me kooky?..
or perhaps just someone who searches for exercise where he can find it?


I used to do that, now I'm into Post Polio Syndrome :-(

That's a major pisser! I have a cousin who went most of her life with
a brace on one knee, but otherwise ok, who entered Post Polio Syndrome,
and found that she could no longer do any kind of repetitive work with
her hands, or back... not even computer work... Her doctor told her that
basically, she has a certain number of movement cycles left in her hands
and back. When they are spent, she will be in full pain, full time.

As I understood things, the sheaths that surround the nerves in her body
are deteriorating. Those that are in areas with a lot of motion are going
faster. When the sheaths are gone, parts of the nerves that are never
supposed to be exposed are going to be fully exposed, and firing at will.

Now, if he sings marching songs, at the top of his lungs, as he mounts
the stairs, that would be kooky!


I don't remember if he screamed anything or not, but he sure drew a
lot of attention, all dressed out in lederhosen and roaring up the
stairs.

Ok, now that is kooky! Lederhosen? Does anybody actually think that
lederhosen are in style for any occasion? ... well, other than during
Octoberfest, that is.

Have you been to one of his "seminars"? I went to one last year that
was here in Phoenix, just to say "Hi". Technical content zero, funny
marketing presentation, yes.

His columns seem to have virtually no technical comment anymore, just
what vitamins he's taking, and how long he can go without taking a
leak ;-)

Hmmm? Sounds thematically similar to some of your postings about
your colon, and stuff ;-)

-Chuck


I don't get paid :-(

...Jim Thompson

You've got a point...

-Chuck

 

[Robert]

"Stuart Brorson" <sdb@cloud9.net> wrote in message
news:11it7qsai47e84b@corp.supernews.com...

Robert <Robert@yahoo.com> wrote:
: "Stuart Brorson" <sdb@cloud9.net> wrote in message
[ . . . .]
: news:11iqrok1ae4pbe7@corp.supernews.com...
:> As for the issue of convergence mentioned above: My experience is
:> that if your SPICE simulation behaves strangely or doesn't converge,
:> it is likely that you have a fundamental problem with your circuit.
:> When a circuit doesn't converge, besides looking for floating nodes, I
:> always examine my circuit thoroughly looking for subtle mess-ups such
:> as two different current sources in series, or two different voltage
:> sources in parallel. More often than not, I find that I have
:> committed some kind of error.
[. . . .]

: Yes your point is general and has nothing to do with what I said.

: Two passive components, a resistor and a cap, left in a netlist
connected
: to ground WITH the other end disconnected causes a circuit to converge
when
: without them it does not. [. . . .]

You are dead wrong. Here's what I wrote above:

:> When a circuit doesn't converge, besides looking for floating
:> nodes . . . . More often than not, I find that I have
:> committed some kind of error.

You miss my point, again.

The circuit converged with the floating nodes. Or now that you've forced me
to go get the book and find his original comments they weren't floating
nodes.

They *were* a resistor and capacitor. And both were connected to one point
and from there tied to ground. Nothing else was connected to that one point
so they had no effect on the circuit action when they were left in.

Bob left them in, the circuit converged. Took them out and the circuit
didn't converge. He said they were originally in the circuit then commented
out. He accidentally removed the asterisk that commented them out. Pg 204 in
the Appendix G "More on Spice", Troubleshooting Analog Circuits, Copyright
1991.

That kind of non-physical behavior from Spice is what he was bitching about.
As well as a whole lot of other stuff that was less useful.

And yes, he was probably using an early version done by the company he
worked for.

A cap connected to GND with the other end open is a floating node.
Avoiding floating nodes is SPICE 101 knowledge.

[snip]

My point is that SPICE is only as good as the models you use. The
models used for IC design are pretty good, whereas those used for
board design are useful but limited.

No. The example that I'm referring to from Bob has nothing to do with
models. Perhaps it has something to do with the early Spice Algorithms.
Don't know. And unlike you, I don't assume I know.

Your arguments about the problems with SPICE are vague,
general, and aren't based on any detailed knowledge of SPICE's methods
and limitations that I can see. They seem to be more of an objection
to computer simulation, and your only evidence is the opinion of Bob
Pease (whose job it is to make outre claims as part of
National's marketing effort).

No. His reported experience with a circuit that has noting to do with your
comments. He may have been wrong. Don't know. Don't think it's that likely
but it's certainly possible.

And no. I don't share his opinion of Spice or other Computer Simulation
tools. Wrong again. I am interested in what went wrong in his sim and what
that says about the algorithms of Spice. If it isn't completely different
from what he was working with.

If you do have something specific and
knowledgable about SPICE's limitations to say, I'd be interested in
hearing it. Otherwise, I'll bid this thread adieu.

Bye.

Anyway, you are welcome to not use SPICE in your design work -- if you
do design at all. Personally, I would like to see you explain to a
job interviewer that you are an electronics engineer who refuses to
use SPICE! *snort*

Enjoy! You seem just as funny from this end.

Harmonic Balance simulators tend to be used more where I worked but the
company originally got PSpice to work on our RF circuits by doing our own
modeling. Spent many years with PSpice and Linear Simulators such as
Touchstone before moving into ADS.

Stuart

 

[Robert]

"Jim Thompson" <thegreatone@example.com> wrote in message
news:nqhti1lkm5p0s6dq9orjbu67d9tqreo34a@4ax.com...

On Mon, 19 Sep 2005 03:55:07 GMT, "Robert" <Robert@yahoo.com> wrote:
[snip]


He castigates Spice to this very day. When we were fellow students at
MIT he was a wee bit kooky (charging up flights of stairs like Teddy
Roosevelt in "Arsenic and Old Lace")... and he's still kooky.

Have you been to one of his "seminars"? I went to one last year that
was here in Phoenix, just to say "Hi". Technical content zero, funny
marketing presentation, yes.

His columns seem to have virtually no technical comment anymore, just
what vitamins he's taking, and how long he can go without taking a
leak ;-)

...Jim Thompson

Doesn't surprise me. Reminds me of people that took a life long aversion to
electronic calculators because slide rules were so much better.

Haven't been to any seminars. Did enjoy some of his technical articles on
Bandgaps and such on the National Web site. But they were mixed in with a
lot more non-technical stuff.

And as for "kooks", I've known a lot worse.

Robert

 

[Anton Erasmus]

On Sun, 18 Sep 2005 06:37:13 GMT, "Robert" <Robert@yahoo.com> wrote:

From what I can recall of Bob's arguments against spice, was the same
as someone saying they do not like Word Processors, becuase they read
a badly written novel. If one uses SPICE incorrectly, then one gets
bogus results, if one understands it's limits and uses it correctly,
then it is a valuable tool.

Regards
Anton Erasmus

Oh, it was a little more than that.

What he said finally drove him up a wall was he was trying to get a circuit
to converge with great frustration and IIRC he came in one morning and the
previous night's run had converged.

When he examined the netlist he found that he had (during the
troubleshooting effort) left in a couple of components (a resistor and
capacitor?) connected to ground with the other ends disconnected. They
should have had no effect on a real circuit.

That made it converge. Taking the components completely out of the circuit
caused the original non-convergence.

That kind of non-real World physical behavior, he calls it "lying", drives
him crazy.

Knowing a little bit about the algorithms of Spice I can perhaps guess that
leaving the circuit components in caused the circuit's Admittance Matrix to
be assembled in a not so ill conditioned State. But it would only be a
guess.

I think a great many (most ?) problems with SPICE and other simulation
programs in general are actually due to problems of the "Floating
Point" data type. AFAIK the total reason for being of the floating
point data type was to get a reasonable range and precision using as
little memory as possible. Today memory is not a problem anymore, and
one can use a fixed point number format with the desired range and
precision necessary for any simulation. A typical construct in many
simulations are:

(x0-x1)/k where x0 and x1 are almost equal. This causes problems in
floating point. If x0 an x1 are say 1.0 and 1.0001 then it is not a
problem. If it is 1000000000.0 and 1000000000.0001, then it bombs out.

I personally think that with todays systems, the use of floating point
should be banned, and in stead large fixed point numbers should be
used. The only disadvantage compared to floating point is that it uses
more memory. (And the little problem that almost no currently used
languages supports them as standard)

Regards
Anton Erasmus

 

[Anton Erasmus]

On Sun, 18 Sep 2005 06:37:13 GMT, "Robert" <Robert@yahoo.com>
wrote:

From what I can recall of Bob's arguments against spice, was the
same
as someone saying they do not like Word Processors, becuase they
read
a badly written novel. If one uses SPICE incorrectly, then one gets
bogus results, if one understands it's limits and uses it correctly,
then it is a valuable tool.

Regards
Anton Erasmus

Oh, it was a little more than that.

What he said finally drove him up a wall was he was trying to get a
circuit
to converge with great frustration and IIRC he came in one morning
and the
previous night's run had converged.

When he examined the netlist he found that he had (during the
troubleshooting effort) left in a couple of components (a resistor
and
capacitor?) connected to ground with the other ends disconnected.
They
should have had no effect on a real circuit.

That made it converge. Taking the components completely out of the
circuit
caused the original non-convergence.

That kind of non-real World physical behavior, he calls it "lying",
drives
him crazy.

Knowing a little bit about the algorithms of Spice I can perhaps
guess that
leaving the circuit components in caused the circuit's Admittance
Matrix to
be assembled in a not so ill conditioned State. But it would only be
a
guess.

I think a great many (most ?) problems with SPICE and other simulation

programs in general are actually due to problems of the "Floating
Point" data type. AFAIK the total reason for being of the floating
point data type was to get a reasonable range and precision using as
little memory as possible. Today memory is not a problem anymore, and
one can use a fixed point number format with the desired range and
precision necessary for any simulation. A typical construct in many
simulations are:

(x0-x1)/k where x0 and x1 are almost equal. This causes problems in
floating point. If x0 an x1 are say 1.0 and 1.0001 then it is not a
problem. If it is 1000000000.0 and 1000000000.0001, then it bombs out.

I personally think that with todays systems, the use of floating point
should be banned, and in stead large fixed point numbers should be
used. The only disadvantage compared to floating point is that it uses
more memory. (And the little problem that almost no currently used
languages supports them as standard)

Regards
Anton Erasmus

 

[Paul Rako]

Wow. What a thread. Well, since I am a pal with both
Bob Pease and Marcello, the guy that gets out National's
SPICE models I suppose I should toss in my two cents.

First, save any effort in contacting National.
We have better things to do then make SPICE models
for 30-year-old parts. It is interesting that just tonight
I was telling Bill Gross and Tim Regen from LT how the
709 was noisy-- I thought I had heard it from Pease
but Bill corrected me--the 741 was noisy, the 709 was
actually pretty good. And yeah, that is what Pease said
as well, I am geting old.

Next, it looks like a simple Google search would have
turned up something but thanks for this little tempest.

Next, there is a huge disconnect with people that use SPICE
for board-level and with people that use SPICE for IC design.
Yeah, just buy a UNIX workstation ($20k) buy Cadence (150k++)
and then run two departments-- one called "Process" and one
called "Modeling" ($5-10M) and yup, after 5 years or so you
will be able to get good results from SPICE. God bless you.

And, if you buy PSPICE for 10k and still spend the 5 or 10 million
those two departments, the modeling and process departments, you
can still get good results for transistor-level simulation. Linear Tech
uses PSPICE for IC design. I have been told that LT-Cad is just a
variant of PSPICE so I am somewhat baffled how people can claim it
works "better".

But, PSPICE will still have trouble converging and doing things with fast
edges or digital (mixed signal) stuff. That may be why National does not
release A to D converter SPICE models. Now with the transistor-level
models, Cadence and a weekend to run, an A to D can yield to SPICE, I
suspect that Thompson guy gets things to work.

But now I leave you IC designers.. .if you want, I can post the twenty
pages of emails I traded with Barrie Gilbert of Analog Devices over this
exact subject.

For board-level SPICE you have to be very careful. National's recent models
are very good. We even model noise-- just watch the Pease Show
(now called "Analog by Design") in a week or two. We just taped it yesterday.
We will show how you can check your models to see if the noise shows up
like in the real world. We will show National's WEBENCH filter designer SPICE
exactly matching Electronics Workbench MultiSim8 SPICE and a real-world
board I built, all agreeing within 1/2 dB. At 10kHz. Next I will build a
15MHz filter. That one will not do so well because all my board
strays will start effecting the circuit. Stay tuned.

But if you are pushing the edge (and why would you need to do
SPICE if you weren't), well, you better be very good to understand
all the limitations of board-level SPICE. You have to make sure
you have good models and test the models against the real world.
Next you have to model the board level stuff. Maybe buy Hyperlynx,
the 48 grand 2 1/2 D field-solver to see trace interaction.
Maxwell's Equations are always right. But you must build exact
3-D models of your circuit and have a lot of computer power.

And before you accuse Pease of being a hopeless curmudgeon, please
separate his "stage persona" from the real guy. I have seen him
tell a young guy who asked about SPICE the perfect response-- use
it carefully and a little at first and build on your correlations to
allow you to SPICE more and more stuff.

And Bob may be a "kook" but he is a truly brilliant man.

So is Barrie Gilbert.

And Jim Thompson.

I just want to get them together in a WWF ring one day.

Now this has been a great thread and it raises some truly great
issues for us at National Semiconductor. So when I go in tomorrow I
will be sure to get some answers to the question that seems most crucial:
"Bob, did you rally wear lederhausen in college?" And if the answer is
yes, "Were they lined with silk like the ones in the National Lampoon
Mr. Rogers' parody?"

Paul




Neil wrote:

Looking for a spice model or subcircuit netlist for the LM709 from National semiconductor. I asked intusoft, cause they have a free model service. I bought their entry level software ICAP/4 8.3.3 from a dealer purchased in 2000. For reasons I won't mention, I was denied the request from their sales department.

I was going to email National, but from what I read in Bob's book "Troubleshooting Analog circuits" he doesn't like S.P.I.C.E. and for good reason...........

Any help on this request would be great....

Thanks Neil

 

[Mike Engelhardt]

Paul,

And, if you buy PSPICE for 10k and still spend the 5
or 10 million those two departments, the modeling and
process departments, you can still get good results for
transistor-level simulation. Linear Tech uses PSPICE
for IC design. I have been told that LT-Cad is just
a variant of PSPICE so I am somewhat baffled how people
can claim it works "better".

You don't know what you're talking about. First of all,
Linear has just about every SPICE simulator available.
The opamp people at Linear do tend to use PSPICE(the
Microsim/OrCAD/Cadence trademark) but that's because
opamps are simple IC's that don't need the best simulation
tools and have been done in PSPICE for very many years.

By LT-Cad, I assume you mean LTspice. The only way
that could be thought of a PSPICE variant would be
because we hired one of the founders of Microsim
at the start of the development of that project to
find out things like how much time and money it took
to develop. LTspice is otherwise a independently
developed version of SPICE and is the world's highest
performance SPICE with regard to speed, accuracy, and
robustness. Just because it runs the PSPICE syntax
extension doesn't mean it's a PSPICE variant. It is
fantastically more accurate that PSPICE. LTspice is
used internally as as upgrade from, e.g., both PSPICE
and hspice for internal IC design. My friends Bill
Gross and Tim Regen are application engineers and
won't know what the IC developers use to design LT
IC's besides possible opamps, not that I believe they
told you the misinformation you posted here.

--Mike

 

[analog]

Paul Rako wrote:

Linear Tech uses PSPICE for IC design.

I have been told by Mike Engelhardt of LTC that this is simply untrue.

I've use both and it most definitely is not.

so I am somewhat baffled how people can claim it works "better".

Obviously you have never tried it. 'Fess up now, how much actual
experience with which flavors of SPICE do you really have?

But, PSPICE will still have trouble converging and doing things with
fast edges or digital (mixed signal) stuff.

LTspice used properly has little problem with such things (but beware,
as always: garbage in - garbage out).

That may be why National does not release A to D converter SPICE
models.

Or maybe they are a bunch of hacks who should swallow their pride
and sign up for an LTspice seminar.

But now I leave you IC designers.. .if you want, I can post the
twenty pages of emails I traded with Barrie Gilbert of Analog
Devices over this exact subject.

There recently was an interesting thread about Barrie Gilbert's AD534
on the LTspice Yahoo user's group.

But if you are pushing the edge (and why would you need to do
SPICE if you weren't), well, you better be very good to understand
all the limitations of board-level SPICE. You have to make sure
you have good models and test the models against the real world.
Next you have to model the board level stuff. Maybe buy Hyperlynx,
the 48 grand 2 1/2 D field-solver to see trace interaction.
Maxwell's Equations are always right. But you must build exact
3-D models of your circuit and have a lot of computer power.

This is more bunk. All you need is a little plain old good engineering
judgment. I regularly get very good agreement with my board level
designs using just that and LTspice. It is fast and accurate, even for
for switching circuit (I rarely use LT models, btw, even though they
are excellent). Also, once one gets the knack (a few simple rules of
good practice and an occasional "trick" or two), LTspice can be made to
converge every time within short order. The methods are based on sound
reason, not magic floating components.

Regards -- analogspiceman

 

[Jim Thompson]

On Thu, 22 Sep 2005 09:47:33 GMT, Paul Rako <s_p_mpa_u_l@yahoo.com>
wrote:

Wow. What a thread. Well, since I am a pal with both
Bob Pease and Marcello, the guy that gets out National's
SPICE models I suppose I should toss in my two cents.

[snip]

And Bob may be a "kook" but he is a truly brilliant man.

So is Barrie Gilbert.

And Jim Thompson.

I just want to get them together in a WWF ring one day.

[snip]

ROTFLMAO! I'll hit 'em with my cane ;-)

(Actually I've never met Barrie, though I've talked to him on the
phone a few times; and was a substitute speaker for him in Australia
back in 1986.)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Kevin Aylward]

Mike Engelhardt wrote:

Paul,

And, if you buy PSPICE for 10k and still spend the 5
or 10 million those two departments, the modeling and
process departments, you can still get good results for
transistor-level simulation. Linear Tech uses PSPICE
for IC design. I have been told that LT-Cad is just
a variant of PSPICE so I am somewhat baffled how people
can claim it works "better".

You don't know what you're talking about. First of all,
Linear has just about every SPICE simulator available.
The opamp people at Linear do tend to use PSPICE(the
Microsim/OrCAD/Cadence trademark) but that's because
opamps are simple IC's that don't need the best simulation
tools and have been done in PSPICE for very many years.

By LT-Cad, I assume you mean LTspice. The only way
that could be thought of a PSPICE variant would be
because we hired one of the founders of Microsim
at the start of the development of that project to
find out things like how much time and money it took
to develop. LTspice is otherwise a independently
developed version of SPICE and is the world's highest
performance SPICE with regard to speed, accuracy, and
robustness.

What I will say here is that a work college, and myself on and off,
have been using LTSpice on some circuits very recently, like currently.
Sure, it converges most of the time when XSpice and Tanner spice, and
any others don't, however it still has problems on some circuits we have
been trying. This is to be compared with TISpice (internal Texas
Instruments spice). In a past life of 3+ years, it *never* failed to
converge, ever. It seemed to have 100 hundreds of algorithms to try
automatically. So, as far as robustness goes, I cant agree. Its good,
but not the best, imo. As for speed, I have never compared it to
TISpice.

Kevin Aylward
informationEXTRACT@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.

 

[Kevin Aylward]

Paul Rako wrote:

And, if you buy PSPICE for 10k and still spend the 5 or 10 million
those two departments, the modeling and process departments, you
can still get good results for transistor-level simulation. Linear
Tech uses PSPICE for IC design. I have been told that LT-Cad is just
a variant of PSPICE so I am somewhat baffled how people can claim it
works "better".

Well, not often I support Mike, but you way off base here. The LTSpice
engine is probably the best there is on PCs as far as simulation speed
and convergence goes. Its the GUI that leaves a lot to be desired.

Kevin Aylward
informationEXTRACT@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.

 

[Paul Rako]

Well, it was an LT guy that told me LT-SPICE was a PSPICE variant but I
don't have the need to trash people, (even anonymously) that some
people do so I will not mention who. I certainly will yield to Mr.
Engelhardt on anything about LT SPICE because my LT friends say
he is THE MAN for this. After all, we know Swanson would rather
work to death one man rather then hire a department. Mike does the work
of two departments and I really respect that. LTSPICE is his baby and
he has a right to be proud of all that work.

Can he tell me the relationship between SwitcherCAD and LTSPICE?
Are they the same thing? And I was once told that LTSPICE does
not allow import of models from other vendors like ADI and National.
Sounds like bunk but it is a proprietary program after all.

BTW Mike, Bill Gross is a recently retired Vice-president and a former
IC designer so I will give him the complement tomorrow that you
consider him an apps guy like me. Swanson really must have you chained to a
workstation.

Now as to my SPICE experience-- well, Berkeley SPICE and Hollerith cards
yeah, a good bit of PSPICE, Intusoft ICAPs, at HP we had this thing
I think called DR Deautch or something that was supposed to converge
really well and my impression of all of them was they are crap.
But this was almost 10 years ago.

I will look for some of the oscillators and stuff that blow up or when
I get around to it publish a circuit I was using SPICE on a few months
ago and everyone can excoriate me just because I didn't know to set
abstol to something and put the .bs command in the deck. Well duh,
whenever I have to slow down edges or loosen up accuracies to get a
convergence it just seems like a real good time to put down the
mouse and pick up a soldering iron. Maybe I am just a scaredy-cat.

I would like to graduate past 7th grade and "you are full of sh1t"
comments so let us act like technical people and deal with facts.

Several years ago EDN magazine did a circuit and gave it to 6
SPICE vendors and Jim Williams at Linear Tech. If I remember about half
of the programs failed to converge and the rest gave wrong results, sometimes
wildly wrong compared to Jim's real board. Was there a memo I missed?
Have models and SPICE engines gotten that much better?

Can anyone really get any kind of mid-range SPICE to deal with non-linear
magnetics? Does anyone trust it to design a complex flyback converter?

Are there really A to D models that give the representative data output of
the real-world signals? Not just the math and correlations involving the
sampled-data theory but the real things going on in the analog and digital
sections? (All board-level models of course, not "real" transistor-level
models.) Does LT offer models of those new fast converters they make?

OK, the SPICE behind National's WEBENCH uses a later version of the SPICE
engine then PSPICE. I have heard one called level or stage two vs a three.
So what are the substantive differences? Does PSPICE suck as much as everything
else Cadence seems to ruin? Maybe I am complaining about my Model T when
everybody else in in a Prius.

I was at Arrowfest tonight where somebody said all SPICE does is solve a matrix.
That is what Berkeley SPICE is. What everyone else is doing is writing
code to try and get the solution to converge when the math blows up.
I had dinner with a guy from PSPICE years ago and he said all of their work is
doing code like that, to keep things from blowing up. How comforting. Is this
wrong?

When I was at HP we were designing automotive diagnostics. I defy anyone to
make a good model of a spark plug gap since most attempts had real trouble
converging and then you realize the flame-front and pressure in the cylinder
affects the signal. Did I miss that memo as well?

People, people, I am not being combative, I work in the on-line SPICE
group at National for crying out loud and really want to use it as much as
possible. Please don't jump on me like I am criticizing your religion or politics
or wife. It just seems like every time I wade into another type of complex circuit
with SPICE I soon feel like I need a CS degree and a month of trial and
it is just so much easier to just build the thing. Remember I am talking
board-level here, not something that you want to simulate to death since there
are 100k of masks at stake. That is why I like our WEBENCH tool. We have
a whole department including a couple of apps guys like me to insure that we
can give good results when we run a simulation. But we build the circuits with the
same exact components and make sure that the SPICE agrees with real-world
values so our customers don't have to. Is everybody out there designing
things with such similarity to their previous designs they know they can
trust the simulations?

Oh, if I have brought Kevin and Mike together then I guess there is
redemption in electronics after all.

Now to the important stuff, maybe I can get Pease to sign-up for Google
Groups but failing that I can at least post his reply to my lederhausen
question today:

=====================================================
*** Hello, Paul,

In reply to your comment.......


**** I do not recall ever wearing or owning Lederhosen, when I was in
college. I recall
specifically that I did not. But I did wear shorts. In the winter. When
bicycling. In the
snow. When I went winter-mountaineering, up in New Hampshire, I wore
shorts plus
long-johns. Red long-johns.


*** I know nothing about silk-lined Lederhosen, and I know nothing
about the Lampoon's parody.

*** Since I never had or wore Lederhosen, then I'm sure that some of the
ones I didn't wear were silk-lined, and
some of the ones I didn't wear were NOT silk-lined. / rap
============================================================

Hey Mike; Tim Regen's birthday tomoroow, come over to Bldg T (The Tastey
Subs on Lawrence Expressway by Arques) and I'll buy you a beer.

Paul



Kevin Aylward wrote:

Paul Rako wrote:


And, if you buy PSPICE for 10k and still spend the 5 or 10 million
those two departments, the modeling and process departments, you
can still get good results for transistor-level simulation. Linear
Tech uses PSPICE for IC design. I have been told that LT-Cad is just
a variant of PSPICE so I am somewhat baffled how people can claim it
works "better".


Well, not often I support Mike, but you way off base here. The LTSpice
engine is probably the best there is on PCs as far as simulation speed
and convergence goes. Its the GUI that leaves a lot to be desired.

Kevin Aylward
informationEXTRACT@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.

 

[Damir]

On Fri, 23 Sep 2005 10:11:23 GMT, Paul Rako <sp_a_mpa_u_l@yahoo.com>
wrote:

snip

Can he tell me the relationship between SwitcherCAD and LTSPICE?
Are they the same thing?

Yes.

Regards,
Damir

 

[Mike Engelhardt]

Paul,

Can he tell me the relationship between SwitcherCAD and LTSPICE?
Are they the same thing?

The name of the program is LTspice/SwitcherCAD III.

And I was once told that LTSPICE does not allow import of
models from other vendors like ADI and National.

More non-sense. Users can import models and since LTspice
knows most Pspice and hspice syntax, it can even run the
imported models without modification. LTspice's SMPS
products are models in a HDL that can't be run in other
SPICE programs because the HDL is above their heads.

BTW Mike, Bill Gross is a recently retired Vice-president
and a former IC designer...

Opps, I was thinking of Tom Gross, the apps guy, who works
in a somewhat closer capacity to Tim Regen, hence I jumped
to him instead of the guy that doesn't work here any more.
Bill Gross was an op amp designer and then VP of that group
that knows little about SPICE and nothing about LTspice.
Yes, do pay him my compliments and mention Boeing SPICE.
He'll tell you lots of non-sense about SPICE.

I was at Arrowfest tonight where somebody said all SPICE
does is solve a matrix. That is what Berkeley SPICE is.

You were at an Arrowfest and somebody said something. Wow.
Most physical simulators solve a matrix, that doesn't
make them varients of each other, it just means it's trying
to solve something. I would suggest that you don't dissertate
on topics that you aren't familiar instead of posting
garbage.

OK, the SPICE behind National's WEBENCH uses a later
version of the SPICE engine then PSPICE. I have heard
one called level or stage two vs a three.

Yes, the people that sell the Webbench thing to National
told me that too. I laughed and walked away.

**** I do not recall ever wearing or owning Lederhosen,
when I was in college. I recall...

Thanks for posting this. I suspected that the Lederhosen
story wasn't true. I find that as my fame, for lack
of a better term, evolves, that there's ever increasing
strange storys about me that never happened or quotes
from me that I never said. The time will come when I'll
join Pease and not read Usenet posts anymore.

--Mike

 

[analog]

Paul Rako wrote:

Well, it was an LT guy that told me LT-SPICE was a PSPICE variant
but I don't have the need to trash people [...]

[cut thinly veiled trashing of various people]

Several years ago EDN magazine did a circuit and gave it to 6 SPICE
vendors and Jim Williams at Linear Tech. If I remember about half
of the programs failed to converge and the rest gave wrong results,
sometimes wildly wrong compared to Jim's real board. Was there a
memo I missed? Have models and SPICE engines gotten that much
better?

LTspice has improved models for inductors and capacitors that allow
realistic parasitics to be entered and computed as an integral part
of the element. This prevents the corresponding branch admittances
from going to zero or infinity for reduced time steps during a
transient analysis, greatly improving run time convergence.

I doubt you or anyone else has a legitimate circuit that would
trip up LTspice.

Can anyone really get any kind of mid-range SPICE to deal with
non-linear magnetics?

LTspice can without breaking a sweat. Download the program and
read the help file topic on L devices.

Regards -- analog

 

[Jim Thompson]

On Fri, 23 Sep 2005 10:11:23 GMT, Paul Rako <sp_a_mpa_u_l@yahoo.com>
wrote:

[snip]

=====================================================
*** Hello, Paul,

In reply to your comment.......


**** I do not recall ever wearing or owning Lederhosen, when I was in
college. I recall
specifically that I did not. But I did wear shorts. In the winter. When
bicycling. In the
snow. When I went winter-mountaineering, up in New Hampshire, I wore
shorts plus
long-johns. Red long-johns.


[snip]

OK, Maybe it was shorts and long-johns ... but definitely very odd
in Massachusetts in wintertime... something about Bob's appearance
definitely stood out, otherwise I wouldn't have so distinctly
remembered just another tech "tool". I didn't even know his name
until I saw him at National.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Kevin Aylward]

"Mike Engelhardt" <nospam@spam.org> wrote in message
news:alSYe.3498$Ba2.928@newssvr27.news.prodigy.net...

Paul,

Can he tell me the relationship between SwitcherCAD and LTSPICE?
Are they the same thing?

The name of the program is LTspice/SwitcherCAD III.

And I was once told that LTSPICE does not allow import of
models from other vendors like ADI and National.

More non-sense. Users can import models and since LTspice
knows most Pspice and hspice syntax,

It don't know HSpice's "hdif" which is used to automatically calculate
AD, AS, PS, and PD. These are absolutely crucial for high speed work.
How come you missed this one? Oh, the last time I checked it didn't
handle Spice's tempcos for mesfets either. Some simulators I know of
handles these...

Tell, you what though, its rather irritating that LTSpice stops dead in
its tracks when it gets a .option it don't know. Like, I have a
floatdata option that simple tells the engine to save files as floats
instead of doubles. In 99% of cases that's all you need, and it halves
the file size. Same comment goes for include files it cant find. How
about just issuing a warning and proceeding on?

Oh..it would be handy if it also supported individual diode instances BV
on their netline to overide the .model data. Makes zeners easier to deal
with, and avoids me having to modify my netlists when I run SS ones
through LT.

Kevin Aylward
informationEXTRACT@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.