Go Back   Home > Forums > >

Solid State Talk all about solid state amplification.

Stability of an amplifier under capacitive loading
Stability of an amplifier under capacitive loading
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
Old 17th September 2020, 01:33 AM   #61
mjona is offline mjona  New Zealand
diyAudio Member
 
Join Date: Jul 2007
Location: Upper Hutt
@knutn,

There are some differences between your simulation in comparison with a Tian plot. There are some examples of this such as here OITPC - Output inclusive TPC (not TMC)
  Reply With Quote
Old 17th September 2020, 09:37 AM   #62
knutn is offline knutn  Norway
diyAudio Member
 
Join Date: Mar 2006
Location: Oslo
i have tried a simulation with KSA1381/KSC3503 and compared to the BD-types, the difference is very small. As long as I have not observed any stability in the built amplifiers (I have made 4 channels), I think the Miller capacitors are large enough.
  Reply With Quote
Old 17th September 2020, 09:51 AM   #63
duncan2 is offline duncan2  United Kingdom
diyAudio Member
 
Join Date: Mar 2013
Location: Scotland.
I was interested in the comment about inter-electrode capacitance in a BD139 and the comment that it could vary from manufacturer to manufacturer .


I could not find any actual info online when it came to the specifications by various companies but came across this-


Application Note No.024 by Infineon which is interesting -

AN024.fm - Parasitic_Capacitances_Bipolar_Transistors_AN024_I nfineon.pdf
  Reply With Quote
Old 17th September 2020, 09:40 PM   #64
N101N is online now N101N
diyAudio Member
 
Join Date: May 2018
It is utterly reprehensible to call the indispensable interelectrode capacitances parasitic. Choose transistors with appropriate interelectrode capacitances for the task. The need for phase compensation is a palpable sign of functional disorder and design failure.
  Reply With Quote
Old 17th September 2020, 10:08 PM   #65
duncan2 is offline duncan2  United Kingdom
diyAudio Member
 
Join Date: Mar 2013
Location: Scotland.
N101N ---if you feel so strongly about the AN of this company why don't you complain to them not me ?
I am sure they will "react " to your criticism , in a perfect/ideal world there would be no capacitance between elements but we are still waiting for the Klingons to land on earth with their "capacitance cloaking device " and put things right on planet earth.



An old English fable has King Canute standing at the sea edge saying " I am King and I command the tide to go back "----it refused and wet his feet --naughty tide ! That was in the 12th Cent. --nothing has changed .


Those statistic are needed in many engineering situations some vital .

Last edited by duncan2; 17th September 2020 at 10:10 PM. Reason: spelling error
  Reply With Quote
Old 17th September 2020, 11:48 PM   #66
N101N is online now N101N
diyAudio Member
 
Join Date: May 2018
I was not complaining to you. A larger amplitude naturally conveys a larger current. The alternative is saturation, a nonfunctioning transistor.

Parasitic capacitances can be unintentionally added in the process of manufacturing, but that`s something else.
  Reply With Quote
Old 18th September 2020, 09:08 AM   #67
knutn is offline knutn  Norway
diyAudio Member
 
Join Date: Mar 2006
Location: Oslo
I think it's better to deal with parasitic capacitances than with Maxwell's equations...
  Reply With Quote
Old 18th September 2020, 09:12 AM   #68
duncan2 is offline duncan2  United Kingdom
diyAudio Member
 
Join Date: Mar 2013
Location: Scotland.
Parasitic capacitance or to put it more gently --"stray capacitance " is a natural occurring engineering phenomenon as we have not reached the stage of perfection.


When an engineer calculates the design of a tube/BJT/Mosfet etc etc this has to be taken into account when designing an electronic component .


Can you explain or show where "Perfect " components are manufactured in this world ?
Or are you complaining about the English grammar as being faulty ?


I could post long lines of university maths on this but will just post a Wiki explanation that keeps it simple.


If a Standard of perfection had been achieved then you could base your point on that , but it hasn't, people like engineering are not perfect.


A capacitor has resistance/capacitance/inductance --even a resistor contains other elements.




Parasitic element (electrical networks - Wikipedia)
  Reply With Quote
Old 18th September 2020, 03:18 PM   #69
spladski is offline spladski  United Kingdom
diyAudio Member
 
Join Date: May 2012
Devices have capacitance. Less concerned what they are called. This is a more interesting comment.

Quote:
Originally Posted by N101N View Post
The need for phase compensation is a palpable sign of functional disorder and design failure.
Isn't that a bit harsh? A means to an end?

Last edited by spladski; 18th September 2020 at 03:19 PM. Reason: Grammar
  Reply With Quote
Old 18th September 2020, 04:15 PM   #70
N101N is online now N101N
diyAudio Member
 
Join Date: May 2018
Anyway, for the BD139, we can firmly expect humongous nonparasitic interelectrode capacitances and parasitic stray capacitances making it unsuitable as a voltage amplifier.

spladski,
I want to call it a clear-cut formal announcement.
  Reply With Quote

Reply


Stability of an amplifier under capacitive loadingHide this!Advertise here!
Thread Tools

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
New Amplifier Build Stability H713 Solid State 37 15th May 2020 09:20 AM
SMPS - Capacitive loading knutn Power Supplies 19 27th August 2019 10:40 PM
Stability into capacitive loads aros71 Tubes / Valves 8 23rd July 2017 06:34 AM
"Tuning phonograph reproduction...capacitive loading & channel balancing" RCAguy Analogue Source 0 3rd March 2015 04:57 PM
good ESL amplifier that works with extreme capacitive loads thadman Solid State 2 1st February 2007 12:20 AM


New To Site? Need Help?

All times are GMT. The time now is 09:46 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki