[sdiy] LTSpice macromodell help

[Tim Stinchcombe]

Darn! Seconds after I hit the 'send' button I re-read your message and
realized that article probably _doesn't_ do what you were asking!

So, I pulled Connelly & Choi off the shelf, and sure enough they use the
diodes+voltage sources method in their op amp macromodel, using a very ideal
diode model:

.model dx d (n=.001)

and then diodes using 'dx' to clamp to the positive and negative rail
respectively. (Hopefully this makes sense this time...).

Tim
__________________________________________________________
Tim Stinchcombe 

Cheltenham, Glos, UK
email: tim102 at tstinchcombe.freeserve.co.uk
www.timstinchcombe.co.uk


> -----Original Message-----
> From: Tim Stinchcombe [mailto:tim102 at tstinchcombe.freeserve.co.uk] 
> Sent: 13 April 2011 22:22
> To: 'Harry Bissell'; 'synthdiy'
> Subject: RE: [sdiy] LTSpice macromodell help
> 
> 
> As well as tanh already suggested, I think the 'arctan' 
> expression used in this nice little article does the job 
> tolerably well too:
> 
> <http://www.edn.com/article/493732-Modular_macromodeling_techn
iques_for_Spice_simulators.php>

PDF version:

http://www.edn.com/contents/images/198891.pdf

Tim
__________________________________________________________
Tim Stinchcombe 

Cheltenham, Glos, UK
email: tim102 at tstinchcombe.freeserve.co.uk
www.timstinchcombe.co.uk


> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of 
> Harry Bissell
> Sent: 13 April 2011 16:48
> To: synthdiy
> Subject: [sdiy] LTSpice macromodell help
> 
> 
> 
> Hi all... yes its synth-related
> 
> I'm trying to come up with a macromodel of a voltage limiter
> circuit. Electronic Workbench includes such a device, LTspice 
> does not.
> 
> The object would be to limit input voltages to a range
> between Vpos and Vneg that I would set. Using a series 
> resistor, two diodes, and two voltage sources is a crude way 
> to do it. I'm looking for something much more elegant.
> 
> Any takers ???
> 
> H^) harry
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