Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #445349 > unrolled thread

Spice Diode Modeling of Forward Overshoot & Reverse Recovery

Back to article view | Back to sci.electronics.design

Contents

  Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-01-30 17:37 -0700
    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-01-30 17:33 -0800
      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-01-30 18:38 -0700
        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-01-30 17:50 -0800
          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-01-30 19:13 -0700
            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Clifford Heath <no.spam@please.net> - 2017-01-31 14:11 +1100
              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-01-30 19:32 -0800
                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Clifford Heath <no.spam@please.net> - 2017-01-31 15:46 +1100
        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery gray_wolf <g_wolf@nospam.com> - 2017-01-31 12:00 -0600
          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-01-31 18:50 -0800
      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-01-31 08:23 -0700
        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-03 17:27 -0800
          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery pcdhobbs@gmail.com - 2017-02-03 17:53 -0800
      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 10:06 -0700
        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-01 09:48 -0800
          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 11:28 -0700
            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-01 18:59 +0000
            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-01 11:02 -0800
              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 12:07 -0700
                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-01 11:15 -0800
                  Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 12:27 -0700
                    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-01 14:45 -0800
                      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 15:54 -0700
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-01 15:37 -0800
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Cursitor Doom <curd@notformail.com> - 2017-02-03 19:54 +0000
            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-03 09:26 -0500
              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Winfield Hill <hill@rowland.harvard.edu> - 2017-02-03 06:36 -0800
                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 09:06 -0700
                  Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 09:30 -0800
              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-03 08:09 -0700
                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-03 11:08 -0500
                  Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-03 09:24 -0700
                    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-03 11:33 -0500
                      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-03 09:43 -0700
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery pcdhobbs@gmail.com - 2017-02-03 08:55 -0800
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-03 17:05 +0000
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-03 16:57 +0000
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Winfield Hill <hill@rowland.harvard.edu> - 2017-02-03 09:20 -0800
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-03 10:58 -0700
                            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-03 10:18 -0800
                              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-03 11:28 -0700
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-03 12:34 -0700
                  Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery bulegoge@columbus.rr.com - 2017-02-03 08:26 -0800
                    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-03 11:34 -0500
                  Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-03 18:31 -0600
                    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery pcdhobbs@gmail.com - 2017-02-03 17:26 -0800
                      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-04 09:08 -0600
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 08:28 -0700
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-04 12:33 -0500
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 10:23 -0800
                            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-04 13:50 -0500
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-04 14:03 -0600
                            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Clifford Heath <no.spam@please.net> - 2017-02-05 08:26 +1100
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 11:14 -0700
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Winfield Hill <hill@rowland.harvard.edu> - 2017-02-04 10:31 -0800
                            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 11:20 -0800
                              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Winfield Hill <hill@rowland.harvard.edu> - 2017-02-04 11:38 -0800
                                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 12:54 -0700
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 11:32 -0700
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-05 09:07 -0700
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery bill.sloman@ieee.org - 2017-02-05 19:01 -0800
                            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-06 10:16 -0700
                              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-06 15:01 -0700
                      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 08:07 -0800
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-04 12:38 -0500
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 10:23 -0800
                    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-03 19:08 -0700
                      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery pcdhobbs@gmail.com - 2017-02-03 18:24 -0800
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-03 20:10 -0700
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-04 01:50 -0500
                            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 08:26 -0700
                              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Winfield Hill <hill@rowland.harvard.edu> - 2017-02-04 07:42 -0800
                                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 09:02 -0700
                                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 09:41 -0700
                                  Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 09:43 -0800
                              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery bill.sloman@ieee.org - 2017-02-04 16:42 -0800
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 08:08 -0800
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery George Herold <gherold@teachspin.com> - 2017-02-04 10:27 -0800
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery George Herold <gherold@teachspin.com> - 2017-02-04 10:34 -0800
                    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 15:44 -0700
                      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery pcdhobbs@gmail.com - 2017-02-04 16:29 -0800
                        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-04 17:32 -0700
                          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 18:58 -0800
          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery JM <dontreplytothis173@gmail.com> - 2017-02-01 19:14 +0000
            Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 12:20 -0700
              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery JM <dontreplytothis173@gmail.com> - 2017-02-01 19:36 +0000
                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery JM <dontreplytothis173@gmail.com> - 2017-02-01 19:45 +0000
                Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 12:45 -0700
              Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-04 09:44 -0800
    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Tim Wescott <tim@seemywebsite.com> - 2017-01-30 20:32 -0600
      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-01-30 19:44 -0700
      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkin@highlandtechnology.com> - 2017-01-30 19:46 -0800
    Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 11:57 -0700
      Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-01 11:03 -0800
        Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-01 12:07 -0700
          Re: Spice Diode Modeling of Forward Overshoot & Reverse Recovery John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-01 11:10 -0800

Page 3 of 5 — ← Prev page 1 2 [3] 4 5  Next page →

#445984

On Fri, 03 Feb 2017 10:18:18 -0800, John Larkin
<jjlarkinxyxy@highlandtechnology.com> wrote:

[snip]
>
>Only insecure people keep boasting about themselves. You are sounding
>like Obama, lots of "I"s.
>
>And what happened to "end of discussion" ?

Why don't you mind your own business?  I was responding to Win's
questions?  And you stuck your butt into the conversation uninvited.

As for "I"... I am the greatest >:-}

I don't know why I ever un-blacklisted you... back you go... your
contributions and comments are worthless.
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

[toc] | [prev] | [next] | [standalone]

#445990

On 3 Feb 2017 09:20:19 -0800, Winfield Hill <hill@rowland.harvard.edu>
wrote:

>Jim Thompson wrote...
>>
>> I work on the basis that my customers are happy with the models
>> I provide, not on any basis that requires your approval.
>
> Are you primarily selling models as an end product,
> or IC designs, in which you use your models to be
> confidant of the result?

I left out, in my previous answer...

I do, often, use behavioral modeling to mock up a system (SOC) and
check out the desired function before converting it to device-level.

Allowed me to catch, for a recent example, a video DC restorer that
clamped the sync tip to ground with a switch is NOT the way to go.

What a switch does is drops the input impedance, requiring a very low
source impedance to drag the clamped signal back positive... otherwise
video distortion.

The proper way is an active loop that uses a current pull-up to stop
the sync tip at the desired level.
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

[toc] | [prev] | [next] | [standalone]

#445949

I just love following these pissing contests

[toc] | [prev] | [next] | [standalone]

#445953

On 02/03/2017 11:26 AM, bulegoge@columbus.rr.com wrote:
> I just love following these pissing contests
>

Does that make you a weenie weenie?  ;)

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[toc] | [prev] | [next] | [standalone]

#446024

"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message 
news:yb2dna0H3qF7NwnFnZ2dnUU7-V3NnZ2d@supernews.com...
> And since it doesn't model actual diffusion behaviour, I have no reason to 
> suppose that it would work in more complicated and realistic situations 
> such as tone bursts in wideband noise.

Phil,

Do you have any example data that illustrates the necessity of solving the 
transport equation exactly?

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com 

[toc] | [prev] | [next] | [standalone]

#446036

>Phil, 

>Do you have any example data that illustrates the necessity of solving the 
>transport equation exactly? 

>Tim 

Well, JL's Grekhov diode pulser is a good one, as are normal SRDs. Even the lowly 1N914 will get charge density waves set up in it if you hit it with a fast ringy pulse, and the details of the response will depend on carrier diffusion.

If I wanted to really model photodetection accurately, I'd need to take into account the 2-1/2 D (i.e. cylindrically symmetric) diffusion problem of carrier transport and light absorption vs depth and wavelength. If the PD had only a single contact rather than a ring, it would be a full 3D problem. This matters a lot, because delay and bandwidth are functions of position, charge distribution, and lateral voltage drops.

And it all depends on the amount of reverse bias. 

I've measured all those effects, but not in nearly adequate detail for modelling. 

Of course if you know the analytic solution to enough special cases, you might possibly be able to cobble up something acceptably general for typical use cases. Optics and radar folks use the Geometric or Physical Theory of Diffraction (GTD/PTD), which works sort of like that. (Stealth technology is based on it, which is why the F-117A is all made of flat facets--you could simulate that on a 1970s computer.)

However, being a transport problem, carrier dynamics is way more complicated than vanilla electromagnetics--it's more like plasma physics. It's simpler because the ions can't move, but more complicated because of traps and defects and stuff. So doing the GTD thing would be hard. 

Cheers

Phil Hobbs  

       

[toc] | [prev] | [next] | [standalone]

#446084

<pcdhobbs@gmail.com> wrote in message 
news:5e74e19b-3950-45dc-923a-89037da2db04@googlegroups.com...
> Well, JL's Grekhov diode pulser is a good one, as are normal SRDs. Even
> the lowly 1N914 will get charge density waves set up in it if you hit it
> with a fast ringy pulse, and the details of the response will depend on
> carrier diffusion.

Okay, but who does that?

I can safely say I have never seen a circuit expose 1N914s to microwaves. 
And anyone who claimed to do so would be seen as retarded.

I see zero value in creating that model.


A much more useful situation is an ordinary power rectifier, where you hit 
it with a "fast ringy pulse" that's produced from a switching inverter. 
"Fast" in quotes because it's maybe tens of nanoseconds at the fastest.

In that regime, transport looks like series inductance, but it's nonlinear 
and non-conservative.  An R||L can crudely replicate part of the behavior 
(like voltage overshoot), but doesn't help with reverse recovery and losses.

There are millions of inverters out there.  This is a high value target.  It 
would be fantastic to have an accurate measure of power dissipation, and 
dynamics, in a simulation of a real, practical circuit.

In the extreme case, one could simulate the electromagnetic and thermal 
response of the entire device, before ever ordering a prototype.

That's a model that has real value.


Phil, are you not motivated by value?  Surely there's nothing worse than 
cooking up some (academically or computationally) amazing toy, and having it 
go nowhere because it's some obscure, useless bit of math that no one needs.

It sounds like you /are/ motivated by value, because accurate PD models 
would be directly useful to you, and of competitive advantage if you had 
them.


So I don't get your obsession with analytical accuracy.  You're being a 
useless dick about it.  If all your PhD has to say is "can't be done", then 
would you please step out of this conversation while the engineers discuss 
the "well what if..."?

Please do correct me if I'm wrong about any of these things: the value of an 
analytical 1N914 model, or a rectifier, or PD, or the reasons for your 
obstinance.

Cheers,

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com 

[toc] | [prev] | [next] | [standalone]

#446090

On Sat, 4 Feb 2017 09:08:44 -0600, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

[snip]
>
>
>So I don't get your obsession with analytical accuracy.  You're being a 
>useless dick about it.  If all your PhD has to say is "can't be done", then 
>would you please step out of this conversation while the engineers discuss 
>the "well what if..."?
>
>Please do correct me if I'm wrong about any of these things: the value of an 
>analytical 1N914 model, or a rectifier, or PD, or the reasons for your 
>obstinance.
>
>Cheers,
>
>Tim

Sno-o-o-o-ort >:-}
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

[toc] | [prev] | [next] | [standalone]

#446113

On 02/04/2017 10:08 AM, Tim Williams wrote:
> <pcdhobbs@gmail.com> wrote in message
> news:5e74e19b-3950-45dc-923a-89037da2db04@googlegroups.com...
>> Well, JL's Grekhov diode pulser is a good one, as are normal SRDs. Even
>> the lowly 1N914 will get charge density waves set up in it if you hit it
>> with a fast ringy pulse, and the details of the response will depend on
>> carrier diffusion.
>
> Okay, but who does that?
>
> I can safely say I have never seen a circuit expose 1N914s to
> microwaves. And anyone who claimed to do so would be seen as retarded.
>
> I see zero value in creating that model.

So don't.  I'm not going to either.  I was asked for situations where 
SPICE would fail, and that's one.  SRDs are another, as I said.  Lots of 
people do expose those to microwaves, after all.  (Improving a SRD 
tripler was one of my very first engineering jobs, back in 1981-2.  I 
did it with a pencil, quite literally.)

Simulating a 10-wavelength piece of coax is still another, except that 
SPICE has been hacked up to deal with that specific transport problem. 
I invite you to try doing that with LCs and see how many it takes.

In other words, if SPICE is all you need for your work, terrific, but 
there's a big world out there.

>
>
> A much more useful situation is an ordinary power rectifier, where you
> hit it with a "fast ringy pulse" that's produced from a switching
> inverter. "Fast" in quotes because it's maybe tens of nanoseconds at the
> fastest.
>
> In that regime, transport looks like series inductance, but it's
> nonlinear and non-conservative.  An R||L can crudely replicate part of
> the behavior (like voltage overshoot), but doesn't help with reverse
> recovery and losses.
>
> There are millions of inverters out there.  This is a high value
> target.  It would be fantastic to have an accurate measure of power
> dissipation, and dynamics, in a simulation of a real, practical circuit.

It sounds like we're in violent agreement now.  Weird.

>
> In the extreme case, one could simulate the electromagnetic and thermal
> response of the entire device, before ever ordering a prototype.

But not in SPICE.

>
> That's a model that has real value.
>
>
> Phil, are you not motivated by value?  Surely there's nothing worse than
> cooking up some (academically or computationally) amazing toy, and
> having it go nowhere because it's some obscure, useless bit of math that
> no one needs.

Tim, with all due respect, that's a very stupid question.  And you seem 
to have an odd definition of "nobody", i.e. "Not Tim Williams".

>
> It sounds like you /are/ motivated by value, because accurate PD models
> would be directly useful to you, and of competitive advantage if you had
> them.
>
>
> So I don't get your obsession with analytical accuracy.  You're being a
> useless dick about it.  If all your PhD has to say is "can't be done",
> then would you please step out of this conversation while the engineers
> discuss the "well what if..."?

If not thinking that circuit design is all there is to engineering is 
"being a useless dick", I plead guilty.

However, I'm pretty sure I've worked in more areas of technology than 
you have, so I have a different view.  One example.

In order to do my antenna coupled tunnel junction silicon photonics 
work, I had to write my own clusterized optimizing EM simulator, which I 
still use and which is superior in many respects to anything you can buy 
at any price.  (It's called POEMS, for "Programmable Optimizing 
Electromagnetic Simulator, and you can read the manual on my web site if 
you're interested.)

It was fun, but it took most of a year, and I wouldn't have done it 
unless I had to--at the time there were zero full 3D EM simulators that 
could optimize device geometry, and I needed one.  (I started with a big 
wrapper script around Berkeley TEMPEST, but that ran out of stooch 
pretty fast because it was single-threaded, which is why I had to do my 
own clusterized FDTD engine.)  It needed to support free-electron 
metals, because I was using gold and silver antennas.  Vanilla FDTD 
can't do those because they have an epsilon that is very nearly a 
negative real number, and the Yee (FDTD) algorithm blows up.  You have 
to add state, usually an auxiliary differential equation, to each volume 
element containing such materials.  Transport could be put in the same 
sort of way if I needed it.

What I got out of it was the opportunity to develop a completely new 
optical interconnection technology that nobody thought would work--until 
it did.  You tell me if that's value or not.

> Please do correct me if I'm wrong about any of these things: the value
> of an analytical 1N914 model, or a rectifier, or PD, or the reasons for
> your obstinance.

I mentioned the 1N914 because that's what Jim's behavioural model is 
trying to represent. Please tell my why you ignored the SRD example.

And where have I said anything about analytical accuracy?

I'm talking about the general tendency of any sort of unphysical fitted 
model (numerical or analytical) to become inaccurate rapidly once you 
exceed some neighbourhood of where the fitting occurred.  This isn't 
specifically a SPICE problem--it happens all over, and usually doesn't 
announce itself.  If there's one thing I hate, it's reasonable-looking 
wrong answers.

My post was a response to Jim's question about exactly why SPICE 
couldn't solve transport problems such as carrier dynamics in silicon.

And merely having a settled opinion that isn't the same as yours is not 
being obstinate.  Neither of us is 18 years old.

Cheers

Phil Hobbs


-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[toc] | [prev] | [next] | [standalone]

#446125

On Sat, 4 Feb 2017 12:33:47 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 02/04/2017 10:08 AM, Tim Williams wrote:
>> <pcdhobbs@gmail.com> wrote in message
>> news:5e74e19b-3950-45dc-923a-89037da2db04@googlegroups.com...
>>> Well, JL's Grekhov diode pulser is a good one, as are normal SRDs. Even
>>> the lowly 1N914 will get charge density waves set up in it if you hit it
>>> with a fast ringy pulse, and the details of the response will depend on
>>> carrier diffusion.
>>
>> Okay, but who does that?
>>
>> I can safely say I have never seen a circuit expose 1N914s to
>> microwaves. And anyone who claimed to do so would be seen as retarded.
>>
>> I see zero value in creating that model.
>
>So don't.  I'm not going to either.  I was asked for situations where 
>SPICE would fail, and that's one.  SRDs are another, as I said.  Lots of 
>people do expose those to microwaves, after all.  (Improving a SRD 
>tripler was one of my very first engineering jobs, back in 1981-2.  I 
>did it with a pencil, quite literally.)
>
>Simulating a 10-wavelength piece of coax is still another, except that 
>SPICE has been hacked up to deal with that specific transport problem. 
>I invite you to try doing that with LCs and see how many it takes.

Hacked or not, LT Spice does transmission lines well, and it's a lot
of fun and education to play with them.

One gotcha: it ignores the impedance of the low side, like a coax
shield, to the universe, so it behaves as if there is an ideal
transformer inside the line. That can be useful in itself.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

[toc] | [prev] | [next] | [standalone]

#446132

On 02/04/2017 01:23 PM, John Larkin wrote:
> On Sat, 4 Feb 2017 12:33:47 -0500, Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
> 
>> On 02/04/2017 10:08 AM, Tim Williams wrote:
>>> <pcdhobbs@gmail.com> wrote in message
>>> news:5e74e19b-3950-45dc-923a-89037da2db04@googlegroups.com...
>>>> Well, JL's Grekhov diode pulser is a good one, as are normal SRDs. Even
>>>> the lowly 1N914 will get charge density waves set up in it if you hit it
>>>> with a fast ringy pulse, and the details of the response will depend on
>>>> carrier diffusion.
>>>
>>> Okay, but who does that?
>>>
>>> I can safely say I have never seen a circuit expose 1N914s to
>>> microwaves. And anyone who claimed to do so would be seen as retarded.
>>>
>>> I see zero value in creating that model.
>>
>> So don't.  I'm not going to either.  I was asked for situations where 
>> SPICE would fail, and that's one.  SRDs are another, as I said.  Lots of 
>> people do expose those to microwaves, after all.  (Improving a SRD 
>> tripler was one of my very first engineering jobs, back in 1981-2.  I 
>> did it with a pencil, quite literally.)
>>
>> Simulating a 10-wavelength piece of coax is still another, except that 
>> SPICE has been hacked up to deal with that specific transport problem. 
>> I invite you to try doing that with LCs and see how many it takes.
> 
> Hacked or not, LT Spice does transmission lines well, and it's a lot
> of fun and education to play with them.
> 
> One gotcha: it ignores the impedance of the low side, like a coax
> shield, to the universe, so it behaves as if there is an ideal
> transformer inside the line. That can be useful in itself.

I've used it fairly often, most recently in that $2 diode sampler, where
I had a 50-ps stub with a mismatched load to help shape the sampling
pulse.  Being able to twiddle that in SPICE was a great
help--breadboarding with 0402s in mid air is hard.  (Chester W and
prototyped it like that back in December--worked great.)

I'm really not knocking LTspice, which is a really nice and very capable
program that I use all the time.  It just isn't the One True Numerical
Solution To Everything, even for circuits.

Cheers

Phil Hobbs


-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

[toc] | [prev] | [next] | [standalone]

#446141

"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message 
news:uMCdnTLjxP3VjQvFnZ2dnUU7-Q_NnZ2d@supernews.com...
> So don't.  I'm not going to either.  I was asked for situations where 
> SPICE would fail, and that's one.

Great!

I don't see anyone arguing that SPICE has doesn't have limitations*.

*Jim might not appreciate the distributed-state property of your examples, 
like TLs or transport.  But that's his problem.

Feel free to call that battle a success. ;-)


> SRDs are another, as I said.  Lots of
> people do expose those to microwaves, after all.  (Improving a SRD tripler 
> was one of my very first engineering jobs, back in 1981-2.  I did it with 
> a pencil, quite literally.)

Okay, cool.

So, how far can you take it?

Suppose a model can be created, and that it has a finite number of free 
variables.  (Whether approximating it in SPICE, or in an environment that 
can actually solve transport phenomena.)

How much data do you need to fix all those parameters?

And how many of those can be read off the datasheet, or measured easily?

Without this critical information, your model is again just a curiosity. 
You have the means to solve it, but no data to enter into the solver.


I suspect this information will be hard to come by, for SRDs.  So, though it 
might be a valuable application, can a usefully accurate model even be 
created (in any environment)?

(And that's without discussing the PCB, where even trace widths and corners 
matter to these picosecond signals.)


> In other words, if SPICE is all you need for your work, terrific, but 
> there's a big world out there.

Tons of things have been simulated successfully with SPICE.  That hasn't 
stopped anyone, despite their models being trivial, utterly unrealistic 
toys. :)


>> Phil, are you not motivated by value?  Surely there's nothing worse than
>> cooking up some (academically or computationally) amazing toy, and
>> having it go nowhere because it's some obscure, useless bit of math that
>> no one needs.
>
> Tim, with all due respect, that's a very stupid question.  And you seem to 
> have an odd definition of "nobody", i.e. "Not Tim Williams".

That wasn't phrased very well on my part -- I wasn't referring to transport 
(or the simulator you made!), but "some amazing toy (...) that no one 
needs".


As long as you've brought it up -- "nobody" is a rather peculiar word.  Its 
meaning seems plain, but it's used most often to mean: "no one that I know 
of".  Language is shitty like that...


> In order to do my antenna coupled tunnel junction silicon photonics work, 
> I had to write my own clusterized optimizing EM simulator, which I
> still use and which is superior in many respects to anything you can buy
> at any price.  (It's called POEMS, for "Programmable Optimizing 
> Electromagnetic Simulator, and you can read the manual on my web site if
> you're interested.)

I've read about it before -- pretty amazing stuff, Phil!


> I mentioned the 1N914 because that's what Jim's behavioural model is 
> trying to represent. Please tell my why you ignored the SRD example.

Duly explained above (I suspect the physics-bits aren't well enough 
documented to make it reasonable to fit, even when a solution can be 
constructed).

So, you have no concerns about the ability to model a 1N914 at limited 
dI/dt..?  Yes it would almost certainly be easier with transport, but if 
that's not in your toolkit, how would you do it?

There seem to be two behaviors of interest here: SRD behavior, and the 
lossy-inductor regime.

Are these behaviors so deeply inseparable, from the underlying phenomenon of 
charge diffusion, that one must solve for that, to have any reasonable 
success at modeling just one or the other?

That seems to be what you're saying, in regards to the 1N914.  Or if not, 
then... please, share the model?! :D


> And where have I said anything about analytical accuracy?
>
> I'm talking about the general tendency of any sort of unphysical fitted 
> model (numerical or analytical) to become inaccurate rapidly once you 
> exceed some neighbourhood of where the fitting occurred.  This isn't 
> specifically a SPICE problem--it happens all over, and usually doesn't 
> announce itself.  If there's one thing I hate, it's reasonable-looking 
> wrong answers.

That's why you put the assumptions in the liner notes!

If there's one thing I hate, it's models that don't even say what their 
limits are!

Trivial example: PCB trace impedance calculators that dutifully spit out 
negative impedances.  Ferrite bead models are awful, too, and never specify 
their useful range.  Let alone nonlinearity.

A diode, modeled with forward recovery, with the attached note saying 
"invalid above 1000 A/us", would be lovely!

Anyone who is sufficiently experienced at SPICE to appreciate the bounds of 
their models, should be grateful to see something like that.  Maybe the 
limit precludes accurate analysis of a particular application (say if a 
particular monolithic switcher accidentally spits out SRD pulses..), but it 
will still be applicable to others (like a more relaxed inverter that has 
enough stray inductance to limit dI/dt).

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com 

[toc] | [prev] | [next] | [standalone]

#446161

On 05/02/17 07:03, Tim Williams wrote:
> "Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
> news:uMCdnTLjxP3VjQvFnZ2dnUU7-Q_NnZ2d@supernews.com...
>> SRDs are another, as I said.  Lots of
>> people do expose those to microwaves, after all.  (Improving a SRD
>> tripler was one of my very first engineering jobs, back in 1981-2.  I
>> did it with a pencil, quite literally.)
>
> Okay, cool.
>
> So, how far can you take it?
>
> Suppose a model can be created, and that it has a finite number of free
> variables.  (Whether approximating it in SPICE, or in an environment
> that can actually solve transport phenomena.)
>
> How much data do you need to fix all those parameters?
>
> And how many of those can be read off the datasheet, or measured easily?
>
> Without this critical information, your model is again just a curiosity.
> You have the means to solve it, but no data to enter into the solver.
>
> I suspect this information will be hard to come by, for SRDs.  So,
> though it might be a valuable application, can a usefully accurate model
> even be created (in any environment)?

Perhaps if there was a model and solver that could use that data,
then there would be more incentive to provide it. Chicken, egg.

Clifford Heath

[toc] | [prev] | [next] | [standalone]

#446123

On Sat, 4 Feb 2017 09:08:44 -0600, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

[snip]
>
>There are millions of inverters out there.  This is a high value target.  It 
>would be fantastic to have an accurate measure of power dissipation, and 
>dynamics, in a simulation of a real, practical circuit.
>
>In the extreme case, one could simulate the electromagnetic and thermal 
>response of the entire device, before ever ordering a prototype.
>
>That's a model that has real value.
>
>
[snip]

They exist.  

For example, Infineon BSC014NE2LSU Spice model includes an elaborate
thermal section.

Unfortunately it was written by "equation bangers" with a lot of IF
statements... a total disaster, so I'm trying to decipher it and
remove the thermal crap so I can manage to do a transient analysis
that doesn't hang :-(
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

[toc] | [prev] | [next] | [standalone]

#446129

Jim Thompson wrote...
> Tim Williams wrote:
>
>[snip]
>>
>> There are millions of inverters out there.  This is a
>> high value target.  It would be fantastic to have an
>> accurate measure of power dissipation, and dynamics,
>> in a simulation of a real, practical circuit.
>
> They exist.  
> For example, Infineon BSC014NE2LSU Spice model includes
> an elaborate thermal section.
>
> Unfortunately it was written by "equation bangers" ...

 Manufacturer's models aren't of much use beyond the
 millisecond territory, because they don't / can't
 include one's heat-sink and PCB thermal information.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#446134

On 4 Feb 2017 10:31:36 -0800, Winfield Hill <hill@rowland.harvard.edu>
wrote:

>Jim Thompson wrote...
>> Tim Williams wrote:
>>
>>[snip]
>>>
>>> There are millions of inverters out there.  This is a
>>> high value target.  It would be fantastic to have an
>>> accurate measure of power dissipation, and dynamics,
>>> in a simulation of a real, practical circuit.
>>
>> They exist.  
>> For example, Infineon BSC014NE2LSU Spice model includes
>> an elaborate thermal section.
>>
>> Unfortunately it was written by "equation bangers" ...
>
> Manufacturer's models aren't of much use beyond the
> millisecond territory, because they don't / can't
> include one's heat-sink and PCB thermal information.

I like to run a realtime junction temperature simulation, analog or
digital, to protect mosfets. That lets one safely push them a lot
harder than a simple current or foldback limiter.

My usual model is scaled power dissipation driving a 1st order lag,
added to heatsink temperature. Tau's are typically in the 100
millisecond range. We calibrate the model by destructive tests.

Here's an analog mosfet power dissipation computer:

https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/Soar_Calc.jpg



-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

[toc] | [prev] | [next] | [standalone]

#446136

John Larkin wrote...
>
> Here's an analog mosfet power dissipation computer:
>https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/Soar_Calc.jpg

 Yes, that's a powerful technique, and it you feed
 it to the right kind of computing circuit, or a
 micro ADC + program, you can protect the MOSFET.


-- 
 Thanks,
    - Win

[toc] | [prev] | [next] | [standalone]

#446139

On 4 Feb 2017 11:38:01 -0800, Winfield Hill <hill@rowland.harvard.edu>
wrote:

>John Larkin wrote...
>>
>> Here's an analog mosfet power dissipation computer:
>>https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/Soar_Calc.jpg
>
> Yes, that's a powerful technique, and it you feed
> it to the right kind of computing circuit, or a
> micro ADC + program, you can protect the MOSFET.

You can also implement the ideal equivalent to that in Spice, add a
heatsink model, and do more things than the crap thermal stuff
presently included in the present models.

I've even implemented SOA display for MOS devices with PSpice (*)
macros, including hot electron problem coverage for very short channel
devices.

(*) Probably doable also in LTspice, I just haven't tried.
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

[toc] | [prev] | [next] | [standalone]

#446130

On Sat, 04 Feb 2017 11:14:24 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Sat, 4 Feb 2017 09:08:44 -0600, "Tim Williams"
><tiwill@seventransistorlabs.com> wrote:
>
>[snip]
>>
>>There are millions of inverters out there.  This is a high value target.  It 
>>would be fantastic to have an accurate measure of power dissipation, and 
>>dynamics, in a simulation of a real, practical circuit.
>>
>>In the extreme case, one could simulate the electromagnetic and thermal 
>>response of the entire device, before ever ordering a prototype.
>>
>>That's a model that has real value.
>>
>>
>[snip]
>
>They exist.  
>
>For example, Infineon BSC014NE2LSU Spice model includes an elaborate
>thermal section.
>
>Unfortunately it was written by "equation bangers" with a lot of IF
>statements... a total disaster, so I'm trying to decipher it and
>remove the thermal crap so I can manage to do a transient analysis
>that doesn't hang :-(
>		
>                                        ...Jim Thompson

Ugh!  Removed the thermal crap and discover that the core model is
LEVEL=1.  How the frick do designers get reliable results with such
crap?
		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

[toc] | [prev] | [next] | [standalone]

#446290

On Sat, 4 Feb 2017 09:08:44 -0600, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

[snip]

[replying to Phil Hobbs]...

>
>So I don't get your obsession with analytical accuracy.  You're being a 
>useless dick about it.  If all your PhD has to say is "can't be done", then 
>would you please step out of this conversation while the engineers discuss 
>the "well what if..."?
>
>Please do correct me if I'm wrong about any of these things: the value of an 
>analytical 1N914 model, or a rectifier, or PD, or the reasons for your 
>obstinance.
>
>Cheers,
>
>Tim

Over dinner last night I was musing about Spice models, my diode model
covering forward overshoot and the resulting hysteria amongst the
"elite".

It struck me that most of the lurkers on this group are engineers.

All that an engineer cares about in regard to a Spice model is that
it's terminal behavior be the same as the real device behaves in his
system/PCB.

The engineer doesn't give a damn whether the model duplicates the
actual physics of the device or not, only that it performs properly.

I would argue that attempting to model a device following the complete
physics of a device produces a cumbersome, difficult to converge and
slow-to-simulate model.

I have 55 "learned"/peer-reviewed papers in my
forward-overshoot/reverse-recovery research file that demonstrate my
point ;-)

I would point out, for instance, that the Spice model for a bipolar
device is not a model that conveys the actual physics of the device,
but a simulatablely-tractable approximation.

The elitists amongst us would insist that a proper model can't be
created unless it "solves" the underlying physics equations.

That is nonsense.

In my musing, not even committed to paper yet, just rolling the
function around in my head, I realized that a controlled charge
accumulation, metered release could easily model the sacred SRD... no
solution of a transport equation involved.

When I posted the waveforms of my forward recovery model, the resident
pompous asshole reared his ugly head and pronounced, "...only
waveforms".

Sonnuva gun, I do believe that's what engineers want to see on their
simulator and their 'scope... not a scrolling useless paper extolling
that the physics equation has been solved.

Lastly, I think many people here are using LTspice, and the elitists
and the resident pompous asshole hang their hats on the results...

I would suggest you check out the accuracy of the resident Spice
models... all based on nearly ideal approximations to emphasize
simulation speed... not accuracy.

HTH >:-}

		
                                        ...Jim Thompson
-- 
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| STV, Queen Creek, AZ 85142    Skype: skypeanalog |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

     Thinking outside the box... producing elegant solutions.

[toc] | [prev] | [next] | [standalone]

Page 3 of 5 — ← Prev page 1 2 [3] 4 5  Next page →

Back to top | Article view | sci.electronics.design

csiph-web