You'd think a Wiki would be the obvious solution, but I tried to use the Wiki here when the whole Lovoltech JFET thing came up. I spent an hour or two trying to get it to admit that I had added my name to the list. It was time wasted. I was not the only one who had trouble.
As is my custom once I reach a certain level of frustration, I drew my sword and applied the Gordian solution to the problem. I pulled out my checkbook, wrote Lovoltech a check, and started taking orders, Wiki be damned--full speed ahead!
I, for one, do not have time to waste on contrary software. I put up with enough of that at work and have no intention of adding to my "learn yet another new computer language/script/application" list unnecessarily. I've seen too many "Oh, no, really, we mean it...this one will be around forever" languages disappear in two years. So far as I can tell, C and Assembler are the only real exceptions for languages. As for applications software...huh!...I just used the latest version of Word the other night for the first time, only to discover that the thing is far from intuitive and furthermore defaults to an incompatible file format. I'll almost certainly be forced to master Word, but it's been a long, long time since I learned new applications and languages for fun.
I'd rather have a life.
Grey
As is my custom once I reach a certain level of frustration, I drew my sword and applied the Gordian solution to the problem. I pulled out my checkbook, wrote Lovoltech a check, and started taking orders, Wiki be damned--full speed ahead!
I, for one, do not have time to waste on contrary software. I put up with enough of that at work and have no intention of adding to my "learn yet another new computer language/script/application" list unnecessarily. I've seen too many "Oh, no, really, we mean it...this one will be around forever" languages disappear in two years. So far as I can tell, C and Assembler are the only real exceptions for languages. As for applications software...huh!...I just used the latest version of Word the other night for the first time, only to discover that the thing is far from intuitive and furthermore defaults to an incompatible file format. I'll almost certainly be forced to master Word, but it's been a long, long time since I learned new applications and languages for fun.
I'd rather have a life.
Grey
Hi Grey,
We should be porting over to a newer version of software soon that works better. It will be tested before it goes into production here. The Wiki may work better then.
I guess this is why we use group buy threads.
-Chris
We should be porting over to a newer version of software soon that works better. It will be tested before it goes into production here. The Wiki may work better then.
I guess this is why we use group buy threads.
-Chris
... what Al means is that in May or so, we asked to split off the spice posts to a new thread. Hugo/Netlist did that. Then we all happily ignored that and continued to post spice related stuff here. Now we asked again to split it off and the mods again did it. They again had to go through the thread post by post and decide to split it off or not. Not a trivial task.
Let's see how far that mod patience stretches...😉
Jan Didden
Let's see how far that mod patience stretches...😉
Jan Didden
janneman said:
If I remember correctly, that thread/split originally developed not by request, but from a feud that developed over the worth of SPICE simulation in audio design (mostly fired by the Golden Eared types that seem to infect these threads with continual dismissive BS directed at those who are clearly more knowledgable and more capable of delving into the technicalities of audio design than they are).
What needs to be made plainly clear is that the SPICE sticky is for a continued discourse on SPICE methods and techniques by those who use it and/or actually want to learn from it – not for moronic BS pseudo-philosophical tirades by those who with no intention or capability of either.
Well, that’s my whinge for the evening.
Cheers,
Glen
janneman said:
Hi Jan,
Good point. It will be interesting to see what happens. The likelihood is that there will continue to be SPICE-related posts that come up in this thread as well as others, as it is a powerful tool in the context of many of the discussions. Indeed, in some cases, some of the newer SPICE issues actually arise as a consequence of some particular discussion.
Cheers,
Bob
Hi Glen,
This is to bad since much valuable information gets lost due to the high volume of posts. The moderator who did split things out again spent a lot of time an effort. Time wasted if people don't look around some. I think we all owe Al (AKA Pinkmouse) a big thank you. Of course Hugo (AKA Netlist) suffered the first time and deserves some appreciation for his work too.
-Chris
Whatever the reason the thread was created, it just proves that people do not often look around for the appropriate place to post on a topic.
This is to bad since much valuable information gets lost due to the high volume of posts. The moderator who did split things out again spent a lot of time an effort. Time wasted if people don't look around some. I think we all owe Al (AKA Pinkmouse) a big thank you. Of course Hugo (AKA Netlist) suffered the first time and deserves some appreciation for his work too.
-Chris
No problem, I much prefer doing positive stuff rather than jumping on miscreants.
Oh, and Jan was very helpful in sorting out post numbers for the split. 😉
I'll give this backslapping a few days, then clean it all out so we can get back to the topic in hand.
Oh, and Jan was very helpful in sorting out post numbers for the split. 😉
I'll give this backslapping a few days, then clean it all out so we can get back to the topic in hand.
Bipolar - MOS crossover issues
Gentlemen:
In the "Negative Feedback..." thread, very interesting work has been presented regarding native (before feedback) ouptut stage distortion but focused on bipolar emitter follower type stages.
Probably this single issue - crossover distortion - merits a similar treatment for MOS output stages, and probably this thread is more appropiate for it, so here is the proposal.
- Simulate similar power level MOS output stages and analyze crossover spectral structure and variation with operating conditions (bias level etc.)
- Simulate both bipolar and MOS output stages but now inculding means to prevent full device cutoff during the opposite cycle.
I could volunteer - with welcome help - to contribute, but unfortunately I am absolutely out of time, and afraid that the temptation even of starting with a rough sim will unavoidably end either derailing more vital duties or cause chronic sleep starvation (let alone divorce issues and such
).
Rodolfo
Gentlemen:
In the "Negative Feedback..." thread, very interesting work has been presented regarding native (before feedback) ouptut stage distortion but focused on bipolar emitter follower type stages.
Probably this single issue - crossover distortion - merits a similar treatment for MOS output stages, and probably this thread is more appropiate for it, so here is the proposal.
- Simulate similar power level MOS output stages and analyze crossover spectral structure and variation with operating conditions (bias level etc.)
- Simulate both bipolar and MOS output stages but now inculding means to prevent full device cutoff during the opposite cycle.
I could volunteer - with welcome help - to contribute, but unfortunately I am absolutely out of time, and afraid that the temptation even of starting with a rough sim will unavoidably end either derailing more vital duties or cause chronic sleep starvation (let alone divorce issues and such
).Rodolfo
Re: Bipolar - MOS crossover issues
Doug Self did much of this work in his book on power amplifiers. If you don't have it, I would strongly recommend purchasing it and reading it.
As far as circuits to "prevent full device cutoff", there have been many, many attempts over the years to do exactly this. They are all inherently non-linear and generally create more problems than they solve. Which is why they are not used more often than they are.
Feel free to come up with the 3,238th variation on this idea, and if you get something that works well, please share it with the rest of us.
ingrast said:
Doug Self did much of this work in his book on power amplifiers. If you don't have it, I would strongly recommend purchasing it and reading it.
As far as circuits to "prevent full device cutoff", there have been many, many attempts over the years to do exactly this. They are all inherently non-linear and generally create more problems than they solve. Which is why they are not used more often than they are.
Feel free to come up with the 3,238th variation on this idea, and if you get something that works well, please share it with the rest of us.
Re: Re: Bipolar - MOS crossover issues
I have not read the book. It seems - as work by Bob and others in the "Negative Feedback ..." thread show - there is some more cloth to cut on the subject.
I do have, but needs far more work than I can afford now to present decent results.
Rodolfo
Charles Hansen said:
I have not read the book. It seems - as work by Bob and others in the "Negative Feedback ..." thread show - there is some more cloth to cut on the subject.
I do have, but needs far more work than I can afford now to present decent results.
Rodolfo
Re: Re: Re: Bipolar - MOS crossover issues
Read the book. It is well worth your time and money.
The bottom line is that there is only one way to avoid crossover distortion -- run pure class A.
There is NO optimal bias point for a MOSFET amplifier (besides pure class A).
For a BJT amplifier, there is an optimal bias point (not as good as pure class A, but consuming MUCH less power).
I like studying history. Then I can learn from the efforts of others instead of re-inventing the wheel.
Nelson Pass developed a circuit to do this over 30 years ago. You can examine the details in his patents, which are available online. But you may notice that Mr. Pass doesn't use these circuits anymore.
As I said in my previous post, they create more problems than they solve.
ingrast said:
Read the book. It is well worth your time and money.
The bottom line is that there is only one way to avoid crossover distortion -- run pure class A.
There is NO optimal bias point for a MOSFET amplifier (besides pure class A).
For a BJT amplifier, there is an optimal bias point (not as good as pure class A, but consuming MUCH less power).
ingrast said:
I like studying history. Then I can learn from the efforts of others instead of re-inventing the wheel.
Nelson Pass developed a circuit to do this over 30 years ago. You can examine the details in his patents, which are available online. But you may notice that Mr. Pass doesn't use these circuits anymore.
As I said in my previous post, they create more problems than they solve.
If I recall correctly, Nelson's patents still switch off both sides, it simply moves the switching from the transistors to diodes. Correct me if my memory has failed me.
There are other designs that use and extra control loop to completely prevent shutoff of one side (one of the monolithic Linear buffers does this, not the LT1166).
In any case, the point about the nonlinearity added by these circuits negating their benefits is quite right. The only benefit is enhanced large signal speed.
There are other designs that use and extra control loop to completely prevent shutoff of one side (one of the monolithic Linear buffers does this, not the LT1166).
In any case, the point about the nonlinearity added by these circuits negating their benefits is quite right. The only benefit is enhanced large signal speed.
Tim__x said:
I haven't looked at Nelson's patent for a while. But this claim was explicitly made in an AES paper in March 1981 by a Sansui engineer. The Sansui circuit was VERY similar to Nelson's patent and seemed to be based on it.
The Sansui circuit was later COPIED exactly by Levinson for their No.33 flagship amplifier (and subsequent models), but claimed as their own invention under the name of "Adaptive Biasing".
>I haven't looked at Nelson's patent for a while. But this claim was explicitly made in an AES paper in March 1981 by a Sansui engineer.
I think that was after Nelson had sold
(or licensed)
the patent to Sansui 🙂
I think that was after Nelson had sold
(or licensed)
the patent to Sansui 🙂
hitsware said:
I'm not sure if you are joking or not. Even with the smiley face, the internet doesn't really convey sarcasm very well.
Nelson never licensed that patent to Sansui. He did license his "Stasis" patent to Nakamichi. Perhaps that is what you are thinking about.
Hi Charles,
It's amazing how much commercial warfare and IP theft goes on in the world. If Sansui engineers wrote a patent application, they are attempting to "own it". Either that or no one searches for prior art on either end in hopes of getting away with it.
Nothing would surprise me any more.
-Chris
It's amazing how much commercial warfare and IP theft goes on in the world. If Sansui engineers wrote a patent application, they are attempting to "own it". Either that or no one searches for prior art on either end in hopes of getting away with it.
Nothing would surprise me any more.
-Chris