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Re: PSpice Logic Levels

>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. > >So, in this past week, I have created some stimulus-level-to-analog >parts with adjustable levels and rise and fall. > >Likewise analog back to 5V logic. > >That way I can patch in 74HC stuff just for behavioral analysis... >speeds things up before I go full device-level in the chip design. > >Any PSpice users that are interested, I'll send you copies for your >symbol libraries... PSpice Schematics only... Capture sucks the big >lemon ;-) > > ...Jim Thompson

So Jim, You have now entered the arcane world of PSpice digital IO, then!

I was one of the last to try to master this insane area of expertise!

It is amazing how, in the midst of all this digital stuff, how much analog there was below the surface of the digital IO. Some of it was sorta kludgy, where they wanted to map EXACTLY the behavior of some of the digital logic's I/O, so added little etable and evalue expressions to it.

So, have you also needed to increase the frequency response of the digital sources, yet? I remember figuring out how to do so in my first few weeks at MicroSim for some customers down at AMCC so that they could model some new ATM chipset outputs and get good eye patterns. They later sent me a tee shirt with an eye pattern on it they were giving out... 8-)

Charlie-- Charlie Edmondson Edmondson Engineering Inc

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Charlie E.
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Yep. Basically I needed to create a small state machine to sequentially bring up some circuitry, make some measurements, compare to previous values, act on that, then go back to sleep.

Since I needed to create some clock sources matching the levels and speeds of my wimpy micro-power stuff, I simply created an interface from STIMx, DIGClock, etc, to device level and vice versa, providing me with level and TR/TF adjustability.

I did it in such a way that I can have multiple logic types simultaneously, say PECL and LoV-CMOS, without having to tamper with all that built-in global-power crap.

I've done a lot of chip work for AMCC... a long time ago... the last was some kind of ethernet controller ;-)

They never gave ME a T-shirt :-(

...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     |
             
   "Sarah Palin is to the left what sunlight is to a vampire."
                          - Cal Thomas
Reply to
Jim Thompson

Is there not TR/TF adjustability in the behavioral model with PSpice? That would be strange.

Maybe they knew it wouldn't fit ...

If it's any comfort, only one client ever gave me a company T-shirt. Thanks to those dreaded toploader washers it recently had to be moved to the stack used for "outdoor work and firewood splitting".

--
Regards, Joerg

http://www.analogconsultants.com/

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Joerg

On a global level, a not-user-friendly adjustment.

The way I did it, once I figured it out, is down-right child's play, and I can have mixed logic just as easy as just one type.

Be nice ;-)

...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     |
             
   "Sarah Palin is to the left what sunlight is to a vampire."
                          - Cal Thomas
Reply to
Jim Thompson

Hmm, LTSpice allows that on a local level. Initially I just didn't know where to enter it but two people sent me a hint. Usenet is wonderful.

[...] 
--
Regards, Joerg

http://www.analogconsultants.com/

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Joerg

In LTspice I believe you're actually talking pulse SOURCES.

I'm talking digital stimulation, arbitrary strings of 1's and 0's converted to specifiable logic levels and TR/TF.

(PSpice is a "mixed-mode" simulator.)

...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     |
             
   "Sarah Palin is to the left what sunlight is to a vampire."
                          - Cal Thomas
Reply to
Jim Thompson

No, logic blocks. Source parameters can also be set, either by text or via an input window, but I wasn't talking about sources.

I just follow the input with a logic gate such as an inverter and then set TR/TF for that particular gate.

--
Regards, Joerg

http://www.analogconsultants.com/

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Joerg

How would you generate 1110101110001011001110001111....?

And then how would you convert 1110101110001011001110001111....

Into 0-to-3.3V CMOS logic with 10ns rise and fall time.

...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     |

                   Liberals are so ignorant...
         They don\'t even know the definition of ignorant
Reply to
Jim Thompson

I don't now, my sequences were simpler and I always concocted them out of several pulse sources and some logic. Maybe it can also read from a file, Helmut Sennewald would know that.

That's easy. Follow it with a buffer and set its TR/TF both to 10nsec.

--
Regards, Joerg

http://www.analogconsultants.com/

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Joerg

Suppose the logic levels were -1V and +1.5V. How would you do that ?:-)

...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     |
             
   "Sarah Palin is to the left what sunlight is to a vampire."
                          - Cal Thomas
Reply to
Jim Thompson

Simple. Go into the component attribute editor (one right click on the device where you want those levels). Left click on SpiceLine2. Enter this:

Vhigh=1.5_Vlow=-1.0

Hit run, pour glass of Merlot :-)

--
Regards, Joerg

http://www.analogconsultants.com/

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Joerg

Not quite, where did you get...

1110101110001011001110001111....

...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     |
             
   "Sarah Palin is to the left what sunlight is to a vampire."
                          - Cal Thomas
Reply to
Jim Thompson

You'd have to ask Helmut, so far my sequences were simple and could be done with 2-3 sources plus some logic. I could probably figure it out but not right now. Got to design a rather unorthodox high voltage circuit, Larkin design process, meaning from CAD straight to fab. One mistake ... phssst ... *BANG* ... sirens wailing ... egg in the face.

--
Regards, Joerg

http://www.analogconsultants.com/

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Joerg

I can type "ON" time, "OFF" time, and then the sequence...

1110101110001011001110001111....

A day later you'll still be trying to find the right pulse source arrangement.

As soon as you get it working I'll decide to change the sequence to...

1110101110001011001010001111.... ;-)

...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     |
             
   "Sarah Palin is to the left what sunlight is to a vampire."
                          - Cal Thomas
Reply to
Jim Thompson

Well, I think the real reason was that they had been asking for a solution to the problem for about two months, and in a couple of days, I had the fix for them. It got them past a big roadblock...

-- Charlie Edmondson Edmondson Engineering Inc

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Reply to
Charlie E.

BTW, Jim, I would like a copy of what you've created. Hopefully one of the guys at EMA will see this, and ask for a copy as well... ;-)

-- Charlie Edmondson Edmondson Engineering Inc

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Reply to
Charlie E.

Well, maybe LTSpice can read in strings, I just don't know yet. Because I never needed it.

--
Regards, Joerg

http://www.analogconsultants.com/

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Joerg

It's in PSpice Schematics format. Is that OK?

...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     |
             
   "Sarah Palin is to the left what sunlight is to a vampire."
                          - Cal Thomas
Reply to
Jim Thompson

It's been fun yanking your chain. NOW go have your glass of Merlot. I'll go open a bottle of Australian Chardonnay ;-)

...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     |
             
   "Sarah Palin is to the left what sunlight is to a vampire."
                          - Cal Thomas
Reply to
Jim Thompson

Nah, got at least 2h of work ahead of me. Then dinner, walking the beasts, bible study, and a nice glass of Sierra Nevada Anniversary Ale.

--
Regards, Joerg

http://www.analogconsultants.com/

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Joerg

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