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Old 21st December 2010, 06:28 PM   #1091
YWN is offline YWN  United Kingdom
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Quote:
Originally Posted by Edmond Stuart View Post
Maybe Ophelia told him this (they know each other).
Yes, we exchanged a couple of emails. You don't want to know what I was told in terms of avoiding this place and in particular certain members. But I don't take anybody's opinion as granted.

I would appreciate if you could stay on topic and make your technical points. I have personally zero interest in yours (and any others) dirty laundry.
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Old 21st December 2010, 07:54 PM   #1092
wahab is offline wahab  Algeria
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Sorry, that would be underdamped. My fault, but then I suspect you understand what I meant. But for you, as for your buddy Edmond, it's just another opportunity to spew some venom.Happy holidays!
Often, you had trouble understanding basic elements that were
indeed right, and then claim that it s nonsensical, yet , you expect
people to automaticaly assume that you are right even when you
write a mistake...

Thanks for so much overvalueing us..
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Old 21st December 2010, 07:58 PM   #1093
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Default Book Supplementary Material Posted

Hi Folks,

Finally I have posted quite a bit of supplemental material for the book on my web site at CordellAudio.com - Home. There will be some more, but this is a pretty big chunk.

The material includes virtually all of the semiconductor models used in the book and a few more. VDMOS models for the MOSFETs are included, both for vertical and lateral MOSFETs. EKV models for the MOSFETs will follow.

Many simulations (about 40) for the tutorial examples in Chapter 19 are included, and are ready to run with model files and plot files included in the simulation directory.

There is also a convenient download link for LTspice and a simple circuit to verify operation of the download. One can be up and running a supplied simulation in about 10 minutes, even without LTspice experience.

There may be a few errors and bugs, so let me know if you have any problems.

Cheers,
Bob
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Old 21st December 2010, 08:10 PM   #1094
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Hi michael, I would respectfully disagree; as a nice to have feature, TMC provides Miller like phase linearity, which TPC doesn't and can't do. But how important is phase linearity in audio, in particular in a power amplifier, I don't know for sure. I though have absolutely no reason to believe it matters at all.

Anybody aware of any relevant commercial power amplifier that uses TPC?
Hi YWN,

Wherever did you get the idea that TMC gives phase linearity which TPC cant provide? This is completely untrue.

TPC gives closed loop phase linearity that is ruler flat within the pass band just as with ordinary single pole miller compensation.


I have demonstrated here

Bob Cordell Interview: Negative Feedback

that TMC is merely TPC applied only to the second and output stages living the input stage to a single pole roll off loop gain response.

Nobody here has persuaded me with hard evidence that limiting TPC to the output stage (TMC) instead of the whole amplifier (TPC) is preferable.

Last edited by michaelkiwanuka; 21st December 2010 at 08:17 PM.
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Old 21st December 2010, 08:26 PM   #1095
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The linear phase feature is very nice to have, however, it should be clearly understood that TMC does not create more loop gain than TPC. It only uses the same amount of loop gain as TPC, but in a different way. Rather than linearizing the entire amp, it uses most of the loop gain as kinda "local feedback" for linearizing the main source of distortions, that is the output stage.
To be precise TMC generates virtually the same total loop gain about the output stage as the equivalent TPC network.

Indeed, TMC applies the TPC loop gain characteristic about the output stage alone while TPC provides the same double-pole loop gain characteristic for the WHOLE amplifier.

TPC is therefore vastly superior to TMC.
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Old 21st December 2010, 08:42 PM   #1096
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Incorrect. TMC behaves as an overdamped (or critically damped) second order system.
Hey syn09,

Wrong! TMC neither behaves as an over-damped system, nor as a critically damped second order system. Apart from minor side effects, TMC behaves as a first order system. BTW, perhaps you don't know it, but a critically damped second order system is not, I repeat is NOT equivalent to a first order system. I also like to remind you that the absence of overshoot does NOT automatically mean that we are dealing here a with critically or under-damped 2nd order system.

Quote:
Originally Posted by YWN View Post
Yes. Actually by varying the TMC resistor, you can get an over- under- or critically damped second order system.
Again, totally wrong!
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Last edited by Edmond Stuart; 21st December 2010 at 08:47 PM.
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Old 21st December 2010, 08:45 PM   #1097
YWN is offline YWN  United Kingdom
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Originally Posted by michaelkiwanuka View Post
To be precise TMC generates virtually the same total loop gain about the output stage as the equivalent TPC network.TPC is therefore vastly superior to TMC.
Hi michael, I would not go that far. I think it's fair to call it "a matter of taste" For audio purposes, the discussion TMC vs. TPC is to me ultimately irrelevant and pointless.

As a student, I am actually curious if TMC can be applied in linear ICs, but understanding that needs some in depth theoretical analysis regarding the limitations, side effects, etc... That's what I am looking for, without much success here People seem to be more concerned about scoring rather than discussing technical matters.
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Old 21st December 2010, 08:51 PM   #1098
YWN is offline YWN  United Kingdom
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Originally Posted by michaelkiwanuka View Post
Hi YWN,

Wherever did you get the idea that TMC gives phase linearity which TPC cant provide? This is completely untrue.

TPC gives closed loop phase linearity that is ruler flat within the pass band just as with ordinary single pole miller compensation.
.
</p>
Hi michael, I was talking about the loop gain phase, that always dips for an effective TPC compensation. Correspondingly, the closed loop TPC compensated amp always overshoots.

A correctly implemented TMC does not phase dip and overshoot in the closed loop.
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Old 21st December 2010, 09:20 PM   #1099
Telstar is offline Telstar  Italy
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Originally Posted by Bob Cordell View Post
Hi Folks,

Finally I have posted quite a bit of supplemental material for the book on my web site at CordellAudio.com - Home. There will be some more, but this is a pretty big chunk.
TYVVM!
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Old 21st December 2010, 11:40 PM   #1100
jcx is offline jcx  United States
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care to choose which of the Yellow traces show a "1st order" loop gain system?

the Vout is ~= output Z due to the AC 1 added to each output Q bias CCS
plotting 1/Vout gives the more familiar looking ~=gain curve presentation of output conductance

(I chose this "odd" approach to ward off arguments over where you should place a simple Middlebrook V test source to properly measure the loop gain - clearly this is a measurement of an external amplifier property and not subject to choice/debate)

the .step statement switches between TPC and TMC and both steps are plotted in yellow

green is the Cdom only output 1/Z

if you want to play you can plot each "step" with V(out)@1, V(out)@2 syntax


its really hard to see why anyone would want to get hung up on the semantics - if you want to call the TMC output step response "almost 1st order" I suppose you could - but I can tell the difference by eyeball in this sim and no ther aspect of TMC can be profitably talked about as a "1st order" system
Attached Images
File Type: png insideTMC.png (62.3 KB, 253 views)
Attached Files
File Type: txt inside_tmc.asc.txt (4.0 KB, 10 views)

Last edited by jcx; 21st December 2010 at 11:53 PM.
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