Re: PSpice Logic Levels

Sep 06, 2008 3 Replies
J

That's tedious to use in a situation with a very large number of transitions.

What I've done in PSpice is take a digital stimulus, say...

110000101011100010....

and feed it thru a magic part that converts it to a pulse train with defined high and low level voltages, and defined rise/fall (all specified via parameter passing, avoiding tedious and error-prone manual value entries).

And it works even when the digital stream may be unpredictable, as in, for example, a delta modulator.

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | It\'s what you learn, after you know it all, that counts.
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P



> Jim Thomps> > Along the lines of the question regarding LTspice logic levels...
> >
> > PSpice has a number of nice digital stimulus "parts", but they kick
> > out _very_fast_ edges at 0-5V logic levels when connected to analog
> > parts.
> >
>
> Can't you set trise and tfall as one can in LTSpice? I just didn't know
> where but one kind reader and Helmut explained it.

Is that a Piece-Wise Linear (PWL) source?


Vxxxx N+ N- PWL(T1 V1 )

Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ Senior staff curmudgeon.
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P

I was thinking about using a macro for converting complex pulse train specifications into a PWL statement. Or a tool with a GUI to enter the waveform.

It works as long as you can define the smallest common interval for your pulse train and then enter enough 1's and 0's to fill up long stretches with no change.

Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ Opinions stated herein are the sole property of the author. Standard disclaimers apply. Celebrity voice impersonated. Batteries not included. Limit one to a customer. Best if used by April 1, 2009. Refrigerate after opening. Void if removed.
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J

I used behavioral modeling techniques.

My approach needs no such information ;-)

[snip SIG left by inadequately functioning newsreader software :-]

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | It\'s what you learn, after you know it all, that counts.
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