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--- In LTspice@..., analogspiceman wrote:

I am in the process of updating the depth and accuracy of the
historical SPICE page over at the LTwiki:

But what I am looking for right now is to complete the section
about PSpice. Specifically, I have no idea who were the people
initial responsible for creating PSpice. [...] Also, I could
not find any information as to when and at what revision Probe
became a part of PSpice. (Perhaps at the initial release?)

Then there is the meaning of name itself. I vaguely recall that
PSpice was at some point called uPspice (the 'u' being a micro
symbol), thus the acronym may have stood for micro-Processor SPICE
(others suggest it meant "Personal SPICE" or "Personal-computer
SPICE").

Okay, after a lead from Tony Casey and some further research, I
found Paul Tuinenga's current website (he was a founder of PSpice),
contacted him and got a very nice response (but he forgot to answer
all the questions!). Here is part of his response that he offer to
be shared:

"PSpice was launched in Jan 1984, with a short paragraph in
Electronics (McGraw Hill) magazine. I have a photocopy of that
announcement, but it's 700 miles away from me just now.

"'P' stands for Personal, as in Personal Computer (PC). MicroSim
(an invented name... having first checked the advertising list in
Byte magazine) stands for SIMulation on MICROprocessors. As it
turns out, the main product idea of the company was a mistake.
Between the summer of 1984 and the spring of 1985, we built an
accelerator based on multiple Intel 8086s (with 8087 floating-point
coprocessors), two complete computers per Multibus board, and systems
with up to 12 boards. The external box attached to an IBM-PC/AT and
provided over 2x the speed of a DEC VAX-11/780 minicomputer (which
many companies were using 24x7 to run UCB SPICE). It was called
PSpice Turbine. We sold one a week after debuting it at an EDN
industrial conference. Then the industry went into a capital-
spending slump and we didn't sell another for the rest of that year.
In the meantime, PSpice the "shrink wrap" software, the sales of
which were to "keep us in baloney sandwiches" until the real product,
the Turbine hardware accelerator, took off. It never did, but every
month the sales of PSpice grew. So we shelved the hardware
development to re-focus on the software e.g. re-writing it from
Fortran into C (then C++ much later)."
_______________________________________________________________

After thanking him for his gracious response, I posed a few more
questions: "When did you first begin working on what was to become
MicroSim/PSpice (and when was MicroSim first officially launched -
1983)? Also, were you the sole (major) founder or did you have
other equal partners?" (Forgot to ask again when Probe became
part of PSpice.)

Anyway, I've updated the LTwiki to include the new information.

!!!Hold on, on just now received an email from Paul Tuinenga.
Here is some of the part okay to be shared:

"The creator of PSpice is Wolfram Blume (BS75 Caltech). He sat in
the office next to mine at Silicon Systems, Inc. (SSi), In 1983,
SSi bought several IBM-PC/XTs. Blume was the in-house maintainer
of UCB SPICE on the Prime minicomputers used for IC design and
layout at that time. SSi developed most of the tools it needed
(and we all take for granted today) because none existed at the
time. For example, SSi was the first to make color plots of IC
layouts, and using stipple patterns for the layers (these overlap
in a visually pleasing way). We also created a layout-versus-
schematic (LVS) that predates by several years anything from the
ECAD vendors.

"Knowing the innards of SPICE, and where the time was spent for
transient simulations, Blume got the idea to see how fast the
IBM-PC was. He tested the speed of MOS level -2 code using the
Microsoft Fortran compiler. As is turns out, that test gave an
optimistic result for Intel processors to accelerate simulations
and thus propelled the idea of MicroSim.

"The problem with SPICE being shoehorned into the PC (640KB max
memory) is SPICE2 was five(?) overlays and no IBM-PC Fortran
compiler had overlay capability. Blume figured out how to replace
those as two programs run in sequence, with the first doing read-
in and checking, then leaving a data structure in memory for the
analyses to operate on in the second program. This is why MicroSim
PSpice had no competition for about two years, until later IBM-PC
Fortran compilers handled overlaying.

"SSi was officially upset with Wolfram and "Blume Engineering"
selling PSpice for $495, and demanded royalties. Blume quit SSi.
Shortly after, he and I met to discuss his situation. He described
this idea for building a hardware accelerator. He's not a hardware
guy, but I am and I knew exactly how to build it. So I quit SSi,
too, and we formed MicroSim in June 1984. Blume was the major
partner."

"Later, when the Turbine fizzled, I turned to software and rewrote
all the device equations into C. Then I created the Parts option
and built up the several thousand standard components library.
Also, I wrote "the book" which eventually went to three editions
(additional material in each), was translated to Japanese and
French, and sold well over 100,000 copies. That last sounds small,
but for technical books, which normally sell in the mid 4-figure
volume range, I am Steven King. OK, I wrote a pretty good book,
but Prentice Hall gets all the credit for pushing it far and wide.
Dr. Richard Newton told me he saw a copy in a Moscow university
office (long before the Soviet empire fell)."
_______________________________________________________________

Below are first the LTwiki SPICE history page introduction, then
the section just about MicroSim PSpice (now needing revision:
_______________________________________________________________

LTspice excels, not only in its technical prowess, but also in its
unique accessibility to and popularity with the masses. This page
highlights the heritage of LTspice, emphasizing both the technical
developments leading up to the current version of LTspice and the
key events and prior trailblazers on the pathway to making SPICE
the dominant simulation platform in the engineering community.

If as its primary original author, Larry Nagel is deservedly
considered "The Father of SPICE" then as its essential enabler,
advocate and general all-round visionary for open source electronic
simulation software, Don Pederson most certainly is SPICE's god-
father. And its two most noteworthy disciples and popularizers
would have to be Paul Tuinenga and Mike Engelhardt. These are men
who clearly could see the power and potential of SPICE, had the
ability to hone it into practical tools and, most importantly had
the genius to make SPICE a comfortable fixture on the majority of
engineering desktops.
_______________________________________________________________

1984: PSpice (Personal-Computer SPICE)

Caltech graduate, Paul Tuinenga (MS78), co-founds MicroSim as V.P. of Technology circa 1983

Developed to run on the first IBM PC, PSpice is initially released in January 1984

Was the first commercial offspring of Berkeley SPICE to run directly on the PC platform

Last FORTRAN version was 2.06 – version 3.00 (Dec 86) was rewritten totally in C, yielding a 20% speed increase

Feedback from a very large customer base led to rapid convergence, speed and feature enhancements

Was the first SPICE program to gain wide acceptance in both industry and academia
- Paul Tuinega's tutorial, SPICE: A Guide to Circuit Simulation and Analysis Using PSpice, (now in its 3rd edition) becomes the "New Testament" of SPICE

KEY EVENT: A zero cost (but node-limited) student version was introduced in 1988
- For the first time, SPICE became truly ubiquitous in the electrical engineering academic and industrial communities

Evolved from Berkeley SPICE 2G, but added many proprietary enhancements
- Dec 86: nonlinear Jiles/Atherton core model, Apr 87: ideal switches, Date?: proprietary IGBT model (and many other enhancements)
- Probe, a waveform viewer module, was added when PC VGA graphics became available
- Schematics, a graphical front end, was added much later with version 5.00 in July 1991

In January 1998 MicroSim was acquired by OrCAD, which itself was subsequently purchased by Cadence Design Systems in July 1999

Hello Jerry,

You left an overdue SPICE-line "wiper={p2}".
I replaced it with .param p2=0.5 just for the case when you
don't want simulate any .step. Now everything is OK.

Files > Temp > Step gain control_p2.zip

Simply unzip this file into a folder and RUN the simulation.

Best regards,
Helmut

Hello Olek,

I remember that I tried and the simulation took too long for
my free time. Please be aware that practically no user of this
group is an employee of LTC.
Why not asking your nearly located FAE (Filed Application Engineer)
from LTC? They may be able to help.

Best regards,
Helmut

PS: I am also not an employee of LTC.


--- In LTspice@..., "oleka111" <oleka111@> wrote:

Really nobody is able to help me ?
I need a solution to get an isolated dc/dc converter with Vin = +8...30V and Vout = +3.2...4.3V at Iout=20 A.
The LTC3765 & 66 chips seems to be a nice solution, but at lower Vin this combo doesn't simulate peoperly/


Thanks in advance, OlekA

--- In LTspice@..., "oleka111" <oleka111@> wrote:

Hello!

I tried to simulate a +9...+30 Vin, +3.5...+4.2 Vout dc/dc converter using LTC3765 & 66 chips.
While it simulates nice using default LT settings as in jigs directory,
any attempt to use lower input voltage in the area +9..12 Vin failed due to abnormal Ndrv pin behaviour.
After several milliseconds of proper work it simply stops feeding Vcc pin through mosfet.

Why it makes this "brownout" ?

Hi All,

Using the examples Helmut directed me to, I put together a circuit, DiodeNoiseCircuit.asc, available in the temp directory. I'm very confused about the need for the capacitor in parallel with the diode. At frequencies where all the current effectively goes through the capacitor and the diode current is effectively zero, the shot noise is correct: sqrt(2*I1*1.602e-19). When the current is all flowing through the diode, which is when I would expect the shot noise to be as calculated, there is no shot noise. Can anyone enlighten me as to why this is the case?

Thanks in advance,
Darren

--- In LTspice@..., "odarren" <odarren@...> wrote:

Hello All,

I have a simple amplifier model using a voltage controlled voltage source with a parallel combination of R and C in the feedback. The noise analysis in LTSpice gives me the expected voltage noise spectral density due to the Johnson noise of the resistance. But I'm trying to add a DC bias current and see the shot noise that results, and it's not working. For example, if I put a 1 Amp DC bias at the negative node of the VCVS, I don't see the output noise change. I also tried using a behavioral model of the current using the white function, and that doesn't produce any noise at the output either.

Does anyone know how to simulate shot noise such as I'm trying to do?

Thanks in advance,
Darren O'Connor