Re: [PEDA] AW: SPICE sim question

2002-06-30 Thread Rolf Molitor

That has nothing to do with circuit simulation.
You were just joking, right ?

Rolf Molitor
Ing.Buero i2e
Remscheid / Germany

-Urspr√ľngliche Nachricht-
Von: Georg Beckmann [EMAIL PROTECTED]
An: 'Protel EDA Forum' [EMAIL PROTECTED]
Gesendet: Samstag, 29. Juni 2002 14:25
Betreff: [PEDA] AW: SPICE sim question


 Hi Gary,

 I want to use the simulator for a Monte carlo analyse for the following
 question.
 To simplify what I mean is, imagine a bridge circuit with four resistors
of
 1% tolerance.
 The circuit is usable, if the bridge - voltage is below a certain limit.
How
 many
 percent of my circuits are usable so that I can decide what's cheaper, to
 throw away
 the bad samples or use of more expensive resistors.

 Do you know how this is done ?
 When I looked at the examples, they only calculated the worst case of a
 circuit, but
 that's not the question, I want to get the distribution of a parameter.

 Georg


 Afshin Salehi wrote:
 
  Just out of curiosity, what types of things do you guys run simulations
 on?

 Amplifiers, linear and switching power supplies, filters, and just about
 anything else that will need tweaking on the bench.

  What drives you to run a simulation on that specific device?

 Testing for stability, what range of component values (tolerance) will
 work reliably, gain, rolloff, keeping signal levels away from the rails
 when designing high gain multi-stage amplifiers, and most important of
 all, gaining rapid insight into what happens when you go outside the
 box.  Also, nothing catches fire or explodes in a simulator!

 How accurate is the simulation to a real world bread boarded device?
 
 Once you learn how to use simulation I would say about 98% accurate, but
 there is a giant proviso here, you must have accurate models and you
 must understand the limitations of the simulation process.  I cannot
 remember the last time a finished product did not behave as the
 simulation did.  The more often you simulate, the better you and your
 results get.

  Jon Elson said it takes a day at first then maybe an hour or so each
time
 to
  remember things, how is that justified to your boss?  I am really just
  curious as to what things people run sims on, how complex those circuits
  that are simulated are, and if the tests are worth while?
 
 I use an old but very capable DOS version ($15,000 when new) of PSPICE.
 I can hand type an ASCII circuit description page in about a half-hour
 (three or four op-amps and twenty or thirty passive parts).  Another
 twenty minutes to patch typos and missed connections. After the circuit
 is running you can do a number of tests in minutes that would take a
 week on the bench.  Whether it is worth the trouble or not all depends
 on what you're doing.  The last thing I did was a strain gauge amplifier
 (something I never did before).  Had the circuit up and running in one
 afternoon, cost of components about $10 versus a packaged product with
 similar specs from Omega for $400.  Is that worthwhile?  My boss thought
 so.

 It all depends...
 Gary Packman

  Thanks,
 
  Afshin
 
  
  * Tracking #: 089C581B73790B40A34A5F9530FFA0A756B58F96
  *
  

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Re: [PEDA] AW: SPICE sim question

2002-06-30 Thread Larry G. Nelson Sr

Monte Carlo analysis is a very good use of spice tools. You have the 
components in the design vary by the tolerance amounts based on 
probabilities and run many simulations to see the distribution of the final 
product output to see what percentage fall outside of the product limits. 
Often you can simplify the circuit and take a yield loss while still 
maximizing profit because of a reduction in component cost. The down side 
is there is still a possibility that all the parts come in skewed to the 
worse case and your yield is zero.
I have used this technique in the past very successfully with PSPICE and 
ISPICE but have never used the Protel simulator yet.


At 07:11 PM 6/30/02 +0200, you wrote:
That has nothing to do with circuit simulation.
You were just joking, right ?

Rolf Molitor
Ing.Buero i2e
Remscheid / Germany

-Urspr√ľngliche Nachricht-
Von: Georg Beckmann [EMAIL PROTECTED]
An: 'Protel EDA Forum' [EMAIL PROTECTED]
Gesendet: Samstag, 29. Juni 2002 14:25
Betreff: [PEDA] AW: SPICE sim question


  Hi Gary,
 
  I want to use the simulator for a Monte carlo analyse for the following
  question.
  To simplify what I mean is, imagine a bridge circuit with four resistors
of
  1% tolerance.
  The circuit is usable, if the bridge - voltage is below a certain limit.
How
  many
  percent of my circuits are usable so that I can decide what's cheaper, to
  throw away
  the bad samples or use of more expensive resistors.
 
  Do you know how this is done ?
  When I looked at the examples, they only calculated the worst case of a
  circuit, but
  that's not the question, I want to get the distribution of a parameter.
 
  Georg
 
 
  Afshin Salehi wrote:
  
   Just out of curiosity, what types of things do you guys run simulations
  on?
 
  Amplifiers, linear and switching power supplies, filters, and just about
  anything else that will need tweaking on the bench.
 
   What drives you to run a simulation on that specific device?
 
  Testing for stability, what range of component values (tolerance) will
  work reliably, gain, rolloff, keeping signal levels away from the rails
  when designing high gain multi-stage amplifiers, and most important of
  all, gaining rapid insight into what happens when you go outside the
  box.  Also, nothing catches fire or explodes in a simulator!
 
  How accurate is the simulation to a real world bread boarded device?
  
  Once you learn how to use simulation I would say about 98% accurate, but
  there is a giant proviso here, you must have accurate models and you
  must understand the limitations of the simulation process.  I cannot
  remember the last time a finished product did not behave as the
  simulation did.  The more often you simulate, the better you and your
  results get.
 
   Jon Elson said it takes a day at first then maybe an hour or so each
time
  to
   remember things, how is that justified to your boss?  I am really just
   curious as to what things people run sims on, how complex those circuits
   that are simulated are, and if the tests are worth while?
  
  I use an old but very capable DOS version ($15,000 when new) of PSPICE.
  I can hand type an ASCII circuit description page in about a half-hour
  (three or four op-amps and twenty or thirty passive parts).  Another
  twenty minutes to patch typos and missed connections. After the circuit
  is running you can do a number of tests in minutes that would take a
  week on the bench.  Whether it is worth the trouble or not all depends
  on what you're doing.  The last thing I did was a strain gauge amplifier
  (something I never did before).  Had the circuit up and running in one
  afternoon, cost of components about $10 versus a packaged product with
  similar specs from Omega for $400.  Is that worthwhile?  My boss thought
  so.
 
  It all depends...
  Gary Packman
 
   Thanks,
  
   Afshin
  
   
   * Tracking #: 089C581B73790B40A34A5F9530FFA0A756B58F96
   *
   

Larry G. Nelson Sr.
mailto:[EMAIL PROTECTED]
http://www.ultranet.com/~nr


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Re: [PEDA] SPICE sim question

2002-06-30 Thread Hugh Stevenson

Good designers rarely simulate their circuitry???

Perhaps 20 years on I am still a newbie!

I find simulation a great tool checking stability of control loops,
finding the optimum resistor for damping, finding out the effect of
parasitic inductance and capacitance, calculating noise gain of
preamps...  I rarely build a lashed up prototype these days.  Its not
usually possible anyway as everything needs a ground plane and
components are too small to modify easily!

If you find simulations taking you too long, get some training to use
them better.  I can simulate things between about 10 and 100 times
faster than building them, and they don't catch fire (important for
power supply work).  They have to be built in the end but my
understanding is usually much better than if I had just done a rough
design and built it.

Cheers, Hugh.

-Original Message-
From: Mira [mailto:[EMAIL PROTECTED]] 
Sent: Sunday, June 30, 2002 10:11 AM
To: Protel EDA Forum
Subject: Re: [PEDA] SPICE sim question


Nice and true thoughts, Gary.
It all depends on:
1. How experienced you are when doing and debugging
your designs.
2. How experienced you are with the simulation tools.
Mainly analog specialists go for this.
Good designers rarely simulate their circuitry, while
newbies start with it to see the effect of changing
the circuitry and the values.
As opposed to what was already said, I can say that
simulations cannot replace the real world. They are
helpful, yes, but only if you know what you are doing. Otherwise they
may put you in a wrong direction. As for the time you'll need to do this
job... it depends on you. I've seen people spending months for
simulations and then twice more time for debugging. 
Luckily there are still bosses, who may afford to pay
for it.

Mira
--- Gary Packman [EMAIL PROTECTED] wrote:
 
 
 Afshin Salehi wrote:
  
  Just out of curiosity, what types of things do you
 guys run simulations on?
 
 Amplifiers, linear and switching power supplies,
 filters, and just about
 anything else that will need tweaking on the bench.
 
  What drives you to run a simulation on that
 specific device?
 
 Testing for stability, what range of component
 values (tolerance) will
 work reliably, gain, rolloff, keeping signal levels
 away from the rails
 when designing high gain multi-stage amplifiers, and
 most important of
 all, gaining rapid insight into what happens when
 you go outside the
 box.  Also, nothing catches fire or explodes in a
 simulator!
 
 How accurate is the simulation to a real world
 bread boarded device?
 
 Once you learn how to use simulation I would say
 about 98% accurate, but
 there is a giant proviso here, you must have
 accurate models and you
 must understand the limitations of the simulation
 process.  I cannot
 remember the last time a finished product did not
 behave as the
 simulation did.  The more often you simulate, the
 better you and your
 results get.
 
  Jon Elson said it takes a day at first then maybe
 an hour or so each time to
  remember things, how is that justified to your
 boss?  I am really just
  curious as to what things people run sims on, how
 complex those circuits
  that are simulated are, and if the tests are worth
 while?
  
 I use an old but very capable DOS version ($15,000
 when new) of PSPICE.
 I can hand type an ASCII circuit description page in
 about a half-hour
 (three or four op-amps and twenty or thirty passive
 parts).  Another
 twenty minutes to patch typos and missed
 connections. After the circuit
 is running you can do a number of tests in minutes
 that would take a
 week on the bench.  Whether it is worth the trouble
 or not all depends
 on what you're doing.  The last thing I did was a
 strain gauge amplifier
 (something I never did before).  Had the circuit up
 and running in one
 afternoon, cost of components about $10 versus a
 packaged product with
 similar specs from Omega for $400.  Is that
 worthwhile?  My boss thought
 so.  
 
 It all depends...
 Gary Packman
 
  Thanks,
  
  Afshin
  
 


  * Tracking #:
 089C581B73790B40A34A5F9530FFA0A756B58F96
  *
 


 
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* Tracking #: 

[PEDA] LT1161 Simulation Model

2002-06-30 Thread Danny Bishop

HI everyone

I would like to find the a simulation model for the LT1161 chip, I have
checked LT and Protel, are there any other avenues to investigate.

Danny



* Tracking #: F2DCC47C4C75004BB70E2F4168CA0E8955DE4973
*


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