Bob Cordell's Power amplifier book - Page 109 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th December 2010, 01:17 PM   #1081
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
Quote:
Originally Posted by panomaniac View Post
Rude remarks removed. Please be polite.
Hi Pano,

I wonder whether you have read this post: Mpp
let's hope the same won't happen with this thread.

Cheers,
E.
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)
  Reply With Quote
Old 21st December 2010, 11:08 AM   #1082
diyAudio Member
 
Join Date: Sep 2006
Quote:
Originally Posted by YWN View Post
</p>
Hi Edmond, that is incorrect. Set aside not all second order systems are overshooting and exhibit a phase dip (but only the overdamped systems, or otherwise said in the frequency domain, with close pole/zero pairs), the Bode integrals theory shows clearly that for a constant unity loop gain frequency, and while keeping the closed loop system stable, you can't get more loop gain than what Miller compensation (as a first order system) can provide. Or otherwise said again, for a first order system, the gain times bandwidth product is a constant.

Obviously TMC provides more loop gain than Miller. That extra loop gain has no other way to appear other than from a pole-pole-zero distribution. That is, roll the gain steep and late (in frequency) and bring the roll off to 20dB/decade around the unity loop gain frequency, to keep the closed system stable.

What you can say is that TMC, as a second order system, can provide the same loop gain as TPC (also a second order system) while not requiring the system to be overdamped. This property is indeed an advantage of TMC over TPC, and is one reason why I was looking after an analysis on if and how TMC implements pole splitting.

I would love to further discuss these things, they are indeed fascinating, but it's holydays and I need to get a life
Hi YWN,

There is a bit of a second-order TPC-like nature to TMC if you recognize that the voltage gain of the output stage is less than unity. With TPC, the T resistor is connected to ground and it has no signal on it (and no bootstrapping). With TMC and a nominal output stage gain of unity (but allowing for injection of distortion components into it), the T resistor is completely bypassed and you merely have a largely pure transistion of Miller take-off point from VAS to output.

If you have a nominal output stage gain of 0.9, you have partial bootstrapping of the T resistor, and this probably gives rise to some TPC-like behavior - the resistor has 10% of the signal across it and it looks similar to a resistor of 10X the value connected to ground.

Just thinking out loud here.

Cheers,
Bob
  Reply With Quote
Old 21st December 2010, 12:02 PM   #1083
WuYit is offline WuYit  Sweden
Banned
 
Join Date: Oct 2010
The transcendental pole-zero cancellation guru says you never stop being amazed by how wishful thinkers make up own rules in order to get theory to match application.
  Reply With Quote
Old 21st December 2010, 12:31 PM   #1084
WuYit is offline WuYit  Sweden
Banned
 
Join Date: Oct 2010
YWN,
on the other hand, under dynamic conditions each stage effects the Loop, each stage is effected by the Loop and vital parameters, like Loop gain, bandwidth, the poles and zeros of the transfer function constantly vary with the load. The Loop is more or less characterized by the formula z = z˛ + c
(L)oops!

Last edited by WuYit; 21st December 2010 at 12:36 PM.
  Reply With Quote
Old 21st December 2010, 01:26 PM   #1085
wahab is offline wahab  Algeria
diyAudio Member
 
Join Date: Nov 2009
Location: algeria/france
Quote:
Originally Posted by YWN View Post
<
Set aside not all second order systems are overshooting and exhibit a phase dip (but only the overdamped systems, or otherwise said in the frequency domain, with close pole/zero pairs),
So overdamped systems are the ones that show overshoots ?...

Yet another completely non sensical sentence..
One has to wonder if it s not pure rethoric...
  Reply With Quote
Old 21st December 2010, 02:22 PM   #1086
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
Quote:
Originally Posted by WuYit View Post
YWN,
.........
The Loop is more or less characterized by the formula z = z˛ + c
(L)oops!
My Loops are characterized by the formula z = mc2
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)
  Reply With Quote
Old 21st December 2010, 02:27 PM   #1087
diyAudio Member
 
Edmond Stuart's Avatar
 
Join Date: Nov 2003
Location: Amsterdam
Quote:
Originally Posted by wahab View Post
So overdamped systems are the ones that show overshoots ?...

Yet another completely non sensical sentence..
One has to wonder if it s not pure rethoric...
Maybe Ophelia told him this (they know each other).
__________________
Een volk dat voor tirannen zwicht, zal meer dan lijf en
goed verliezen dan dooft het licht…(H.M. van Randwijk)
  Reply With Quote
Old 21st December 2010, 05:13 PM   #1088
YWN is offline YWN  United Kingdom
Account disabled at member's request
 
Join Date: Jun 2010
Location: UK
Quote:
Originally Posted by wahab View Post
So overdamped systems are the ones that show overshoots ?...

Yet another completely non sensical sentence..
One has to wonder if it s not pure rethoric...
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!
  Reply With Quote
Old 21st December 2010, 05:17 PM   #1089
YWN is offline YWN  United Kingdom
Account disabled at member's request
 
Join Date: Jun 2010
Location: UK
Quote:
Originally Posted by Edmond Stuart View Post
Therefore TMC behaves like a 1st order system. period
Incorrect. TMC behaves as an overdamped (or critically damped) second order system.
  Reply With Quote
Old 21st December 2010, 05:20 PM   #1090
YWN is offline YWN  United Kingdom
Account disabled at member's request
 
Join Date: Jun 2010
Location: UK
Quote:
Originally Posted by Bob Cordell View Post
Hi YWN,

If you have a nominal output stage gain of 0.9, you have partial bootstrapping of the T resistor, and this probably gives rise to some TPC-like behavior - the resistor has 10% of the signal across it and it looks similar to a resistor of 10X the value connected to ground.
</p>
Yes. Actually by varying the TMC resistor, you can get an over- under- or critically damped second order system.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Another realization of Bob Cordell's THD Analyzer giulianodes Equipment & Tools 37 9th October 2013 02:48 AM
best audio amplifier book?? Bouvett Everything Else 30 13th August 2012 02:43 AM
Amplifier Design Book pixie Everything Else 27 11th June 2010 08:36 PM
Project 11.1 from Slone "High-Power Amplifier" Book Karl71 Solid State 46 6th October 2008 03:47 AM
book-audio power amplifier by Douglas Self mikee12345 Solid State 8 16th November 2003 01:16 AM


New To Site? Need Help?

All times are GMT. The time now is 02:25 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2