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Old 13th July 2007, 08:57 PM   #171
andy_c is offline andy_c  United States
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Default Re: Toshiba 2SJ201 & 2SK1530

Quote:
Originally posted by Bob Cordell
Does anybody have a good source for the Toshiba power MOSFETs 2SJ201 and 2SK150?

(...)

BTW, I contacted Toshiba re SPICE models for them, and of course they don't have them. Anyone got some?
Hi Bob,

Did you mean the 2SK1530? The models for these devices were discussed earlier in this thread here . I haven't done extensive verification of these, but I have done some capacitance sims. Also, in private email to Edmond, who came up with the original models, I sent him some plots of Cgd vs Vgd. These are in Excel spreadsheets attached to this post.
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File Type: zip toshiba_fets.zip (6.4 KB, 131 views)
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Old 14th July 2007, 04:11 AM   #172
andy_c is offline andy_c  United States
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I think people in the business of selling mysticism are prone to use the anti-SPICE argument as a political platform to create a false dichotomy between "the mystical" and "the superficial".

The idea of model development is to continually refine and improve the mathematical models of devices in order to get the most accurate simulations possible. Will they ever be perfect? No. But the better they get, the more ridiculous the false dichotomy becomes.
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Old 14th July 2007, 05:23 AM   #173
PB2 is offline PB2  United States
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Quote:
Originally posted by john curl
Bob, I tend to design my audio products for REASONABLE WORST CASE. This is not typical, BUT realistic worst case reproduction.
Think of the difference in design between a Renault Dauphine and a Porsche, even from the same time period.
The Porsche is designed to go into a controlled skid, and a Renault is designed to roll over.
Are we talking rear engine Porsche or front engine? We won't bother with the mid engine 914 which really should have been a Volkswagen.
It would have to be rear I'd say for the time period that you are referring to and it actually had rather strange characteristics when the rear end broke loose. Very quirky and unnatural. After all it was the evolution of a Volkswagen, at least the conceptual design. Not to be picky or anything, just sayin' ...

"The rear-bias was always a problem to 911's handling. Any tail-heavy cars have a tendency to oversteer. If such oversteer is not adequately suppressed, lost of control may occur. "
From: http://www.autozine.org/911/911_5.htm

Porsche ... Controlled skid, I don't think so ...

And I can't believe I took the time to write this, LOL!

SPICE has it's purpose as does prototyping. The productive discussion would be to further the understanding of the strengths and weaknesses of each.

Pete B.
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Old 14th July 2007, 05:39 AM   #174
PB2 is offline PB2  United States
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Remember this:
http://www.bostonaudiosociety.org/ba...x_testing2.htm

I wonder if Ivor T. uses SPICE, I seriously doubt it.
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Old 14th July 2007, 03:17 PM   #175
PB2 is offline PB2  United States
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Quote:
Originally posted by john curl
Ever drive a 924 or a 944? That was essentially what I was referring to. Why quibble? Learn and grow! For the record, I owned and drove a Renault Dauphine approximately 95,000 miles in 5 years and I know its characteristics well. I have also owned a Porsche 924 and currently own a 944. I know their driving characterisics just as well.

I owned two 944s, yeah I've driven them some.

The 924 should have been a Volkswagen, and probably the 944 also. The 911 series is what made Porsche the legendary company. You stated from the same time frame, and the 944 is certainly not from the same time frame, change your story often?:
http://en.wikipedia.org/wiki/Renault_Dauphine

And by the way, SPICE is not emulation, as you seem to repeatedly state, rather it is simulation:
http://en.wikipedia.org/wiki/Emulator

Quickturn is an emulation system where programmable logic is used typically, to emulate the behavior of a chip or system. My cache controller chip design for example worked first time in both emulation (Quickturn) and the real chip because I took the time to learn and use modern tools such as simulation. My NTSC Video encoder also worked in first pass silicon without any engineering changes. Modern tools are what make first pass success possible.

I hear that the first Pentium was emulated in a large array of Quickturn boxes. They learned their lesson using cut and try with the 286 which was seriously late to market, and never did work right in Protected mode.

Learn and grow you say? Seems I do that fairly regularly, what about you?

Let me repeat my position just in case it goes unnoticed:
"SPICE has it's purpose as does prototyping. The productive discussion would be to further the understanding of the strengths and weaknesses of each. "

I have suggested rapid prototyping on occassion when it made sense.

Pete B.
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Old 14th July 2007, 05:30 PM   #176
PB2 is offline PB2  United States
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Quote:
Originally posted by john curl
I am trying to make a comparison between indifferent phono design and excellent phono design by using autos as a comparison. The name Porsche is written on both the 924 and 944 in prominent letters and they were at least 'set up' by Porsche at the factory to be able to go into a controlled drift with a competent driver at the wheel.
The Renault would actually roll over, if you got into a tight spot, rather than drift. That is a serious design difference. When I switched over to Pirelli tires on the Renault, it too could be put into a controlled drift as they would break away into a drift, before the Renault started to think about rolling over.
The best phono design, in my opinion, requires that you accept what is actually being developed by the phono cartridge in reasonable worst-case conditions and design the phono stage to not clip, slew rate limit, or even significantly distort during cartridge mistracking.
Bob appears to ignore mistrackiing as a design reference. That is the difference in our positions.
I got the point of your auto analogy from the start, and I do agree with having a good amount of design margin and handling misuse conditions gracefully. However, the war and cheap shots from some members of the camps are unfortunate. Makes constructive discussion difficult.

Just wanted to point out the Porsche thing, and the sweeping statements about SPICE users.

Using SPICE is not to be taken lightly, we often have a team of tools people for validation and to make sure that everything is in proper working order. I welcome having a SPICE Guru because it is a difficult task to validate models. If someone enjoys the technical challenge and contributes I welcome the input.

I also welcome your positive technical input regarding your experience John, and do appreciate it.

Pete B.
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Old 15th July 2007, 05:09 AM   #177
Tim__x is offline Tim__x  Canada
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Slowly (assuming you were asking me) Though I did come up with a neat little cascode that cancels (yes cancels, not reduces)one more source of distortion.

I don't claim to a spice expert (or any other kind of expert), but I do want to point out the potential of spice. All the complaints people have with spice are really complaints about how people use it.

As an experiment for my own edification, I just did a Monte Carlo of an idealized LTP pair: just two transistors (2n3904s using On Semi's model), an ideal current source, an ideal differential current to voltage converter and an input stimulus such that the Ic swung 10%.

I kept one transistor constant and used spice to vary every parameter of the other +-20%. Across 50 runs the second harmonic varied between -50db and -81db, averaging -61db, with perfectly matched transistors it was -95db (common-mode distortion).

The 34db difference does show the need for balanced circuits to be intentionally imbalanced in simulation.
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Old 15th July 2007, 06:14 PM   #178
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Quote:
Originally posted by Tim__x
Slowly (assuming you were asking me) Though I did come up with a neat little cascode that cancels (yes cancels, not reduces)one more source of distortion.

I don't claim to a spice expert (or any other kind of expert), but I do want to point out the potential of spice. All the complaints people have with spice are really complaints about how people use it.

As an experiment for my own edification, I just did a Monte Carlo of an idealized LTP pair: just two transistors (2n3904s using On Semi's model), an ideal current source, an ideal differential current to voltage converter and an input stimulus such that the Ic swung 10%.

I kept one transistor constant and used spice to vary every parameter of the other +-20%. Across 50 runs the second harmonic varied between -50db and -81db, averaging -61db, with perfectly matched transistors it was -95db (common-mode distortion).

The 34db difference does show the need for balanced circuits to be intentionally imbalanced in simulation.

Hi Tim,

This is a very interesting experience and a good example of how SPICE can be used to explore the design space and also the effect of real-world imperfections.

When you were varying all those parameters by +/- 20%, were the two collector currents kept identical? I'm usually under the impression that, because of the nature of the exponential Vbe characteristic, matching the collector currents is pretty much the most important thing in a diff pair, and am also under the impression that if the collector currents are matched, they are pretty tolerant of some other mismatches in parameters. What did you find?

Thanks,
Bob

PS: one area in which I find SPICE especially useful is in analysis of feedback compensation circuits and also analysis of circuitry that might be prone to local oscillations.
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Old 15th July 2007, 07:09 PM   #179
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Quote:
Originally posted by Tim__x
Slowly (assuming you were asking me) Though I did come up with a neat little cascode that cancels (yes cancels, not reduces)one more source of distortion.

I don't claim to a spice expert (or any other kind of expert), but I do want to point out the potential of spice. All the complaints people have with spice are really complaints about how people use it.

As an experiment for my own edification, I just did a Monte Carlo of an idealized LTP pair: just two transistors (2n3904s using On Semi's model), an ideal current source, an ideal differential current to voltage converter and an input stimulus such that the Ic swung 10%.

I kept one transistor constant and used spice to vary every parameter of the other +-20%. Across 50 runs the second harmonic varied between -50db and -81db, averaging -61db, with perfectly matched transistors it was -95db (common-mode distortion).

The 34db difference does show the need for balanced circuits to be intentionally imbalanced in simulation.

Yes, I was asking. The cross quad looks odd to me, and I have
yet to wrap my head around it.

That is an interesting example of Monte Carlo, and is appreciated.

At the same time, I have several examples of simulations which
don't give correct results, and I have to admit that I'm not an
expert either.

My favorite is a MicroCap9 sim of an ordinary op amp in a
Sallen Key type 2 pole high pass with gain in the op amp. As
you raise the gain, the Q increases and a peak forms at the
knee, and as you raise the gain further, it turns into an
oscillator. Try as I might, I can't make the simulation oscillate,
although it behaves as expected up to that point.

Any ideas?

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Old 16th July 2007, 06:45 PM   #180
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Thanks Nelson for the tip on Microcap. I have a very early version that works directly with a Mac and I have used it for almost 20 years. It does what I need, mostly. You know AC and transient analysis.
However, I still cannot get my Mac to Windows emulator working properly, and trying to install it the other day with the expert help of a friend, crashed my operating system and I am still recovering. I also misplaced my codes for the Windows operating program, so I have to find it first, before I can make the emulator try to make the Spice simulation work. In any case, thanks for the input.
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