HSPICE to PSPICE Conversion

Ok,

I actually figured everything out except for one line...

E1 out ref in+ in- MAX=5V MIN=-5V opamp_gain

I'm trying to code a VCVS with maximum and minimum output values, but PSPICE rejects the MAX and MIN parts. Any ideas?

Thanks

Gish wrote:

What's the model for 'my_opamp' subcircuit (subckt)?

I think that PSpice doesn't support MAX and MIN values.

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Here are a few of the operators in PSpice BEHAVIORAL elements:

LIMIT(x,min,max) result is min if x < min, max if x > max, and x otherwise

MAX(x,y) maximum of x and y

MIN(x,y) minimum of x and y

In addition you must use the BEHAVIORAL syntax of the E-source

So the correct expression for E1 is:

E1 out ref VALUE = {LIMIT((opamp_gain*V(in+,in-)),MIN,MAX)}

..PARAM MAX=5V MIN=-5V opamp_gain=100K

(Or put the numerics directly in the expression.)

This is convergence risk using mathematical limits, since they are hard, and derivatives don't exist at the limit points.

I prefer using the TANH expression:

E1 1 0 VALUE {(tanh(A*V(INP,INN))+1)/2} E2 OUT 0 VALUE {V(1,0)*(VP-VN)+VN}

..PARAM A=100K ; OpAmp Gain ..PARAM VP=+5V ; Positive Limit ..PARAM VN=-5V ; Negative Limit

(Note that exact gain is an interaction between A, VP, and VN (E1 produces 0 ->1), but I'm still too sleepy this morning to make an exact expression :)

...Jim Thompson

Are you using PSpice "raw", i.e. without schematic capture?

Both PSpice Schematics and Capture (gag me with a spoon) have the correct netlist TEMPLATE contained within the symbol.

(Not that I should be one to criticize. I went for MANY years drawing schematics with pencil and paper, numbering nodes, hand-typing netlists, and batch-loading into Berkeley Spice 2G6 on an old VAX, IIRC, 1170. Then I discovered PC's and bought my first 386 for $6K... cheap because it was a clone :-)

...Jim Thompson

Sun, 20 Feb 2005 10:40:10 -0700: Jim Thompson (----> snipped-for-privacy@example.com) ----> sci.electronics.cad @ :

I sometimes end up doing this, even though I have 2 schematic editors here (LTspice and SIMetrix Intro).