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What's the best way of creating an opamp model if the manufacturer
does not have a spice model for it?
Thanx,
-Jon

--- In LTspice@..., "oztek_jtg <jgraham@o...>"
<jgraham@o...> wrote:

What's the best way of creating an opamp model if the manufacturer
does not have a spice model for it?
Thanx,
-Jon

If you're employed as a design engineer, sometimes you can get a
vendor to develop a model on request.

Mere mortals have to use what's available on published data sheets
and try to fit it into the component values of standard macromodel
topologies. Several published works deal with this. The seminal
paper is useful and readable, but later works are much better:

'Macromodeling of Integrated Circuit Operational Amplifiers', (Boyle
et al), IEEE Journal of Solid State Circuits vol SC-9 (Dec 1974)

Copy it from the library of any University near you that has an
Engineering school, or decent Physics department. (In this area,
that's Washington Univ or Univ of Mo - St Louis; even the St Louis
Public Library has a LOT(!!) of the IEEE pubs on microform.) Walk
in like you own the place and ask for help finding the right shelves
- no librarian has ever thrown out anybody who was behaving himself.

Three manufacturers have published app notes that do a pretty good job
of linking data sheets to model parameters via equations:

'SPICE-Compatible Op Amp Macro-Models', (Alexander & Bowers), Analog
Devices Application Note AN-138 (1990)
(originally published as 'Designer's Guide to SPICE-Compatible
Macromodels', in Electronic Design News (EDN), vol 35 no 4, Feb 15
1990 (Part 1) & no 5, Mar 1 1990 (Part 2))

'Using the LTC Op Amp Macromodels', (Jung), Linear Technology
Application Note 48 (1991)

'Development of an Extensive SPICE Macromodel for "Current-Feedback"
Amplifiers', National Semiconductor Application Note 840 (Jul 1992)

These are all available as PDF files from the respective vendors web
sites, and other places on the web. Don't dismiss the National
paper because it says "Current-Feedback" - most of what it says
applies to modeling ANY op-amp.

Along the same lines, you might look at:

'A Comprehensive Simulation Macromodel for "Current-Feedback"
Operational Amplifiers', (Bowers), IEE Procedings vol 137 pg 137-145
(Apr 1990)

Note that this is published by the U.K. IEE, not the American IEEE!

Dale

--- In LTspice@..., "Dale <dchishol@c...>" <dchishol@c...>
wrote:

--- In LTspice@..., "oztek_jtg <jgraham@o...>"
<jgraham@o...> wrote:

What's the best way of creating an opamp model if the manufacturer
does not have a spice model for it?
Thanx,
-Jon

If you're employed as a design engineer, sometimes you can get a
vendor to develop a model on request.

Mere mortals have to use what's available on published data sheets
and try to fit it into the component values of standard macromodel
topologies. Several published works deal with this.

- - - > SNIP < - - -

If anybody knows of more recent works than what I previously cited, I
am definitely interested in learning about them!!

I've been putting together an EXCEL spreadsheet that takes a couple
dozen values from the datasheet & spits out a macromodel text file,
but it's not yet ready for general distribution.

Dale

2. constructing opamp models
From: "oztek_jtg <jgraham@...>"

<jgraham@...>

Try these sites for more information:






Peter