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Class D Switching Power Amplifiers and Power D/A conversion

Class D investigation.
Class D investigation.
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Old 6th January 2017, 02:12 PM   #21
kees52 is offline kees52  Netherlands
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For a discrete fast output stage the pair 2SA1020 and 2SC2655 are very good shaper bjt for a discrete gate driver, use of a irfp240 who has quite low capacitance for the phillips UCD example to get it much faster,
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Old 6th January 2017, 06:01 PM   #22
Pafi is offline Pafi  Hungary
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Quote:
Originally Posted by kees52 View Post
Thank you Pafi for your responds.

I do not need much help and you have more things to do then help me, I am already thankfull to give me some hints about the D amps, she can be very complicated.

I do find 105 102 nS for the powercomparor quite fast, as say someone that it is old, the most amplifier designs are old, even D come from 1952.

Oke, Last quenstion R22 and 24 from what schematic?
The original, in the article you linked. Your schematic is unreadable for that part.

Quote:
I did not read it because I have not seen it, that is why I have this tread, so things get not everywhere .
Sorry, I answered there to your question:
ucd 25 watts to 1200 watts using 2 mosfets

Quote:
As for the Tas power modules these are noce but I like the challence of discrete stuff, and special try to lower distortions, so I di read a lot.. for discrete power modules I do set dead time with the gate resistors, this works fine and is simple.

Maybe this gate driver is better, because of higher voltages., IR2011S

regards
If you need high power, yes. But for high quality...
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Old 8th January 2017, 07:20 PM   #23
kees52 is offline kees52  Netherlands
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I do now if I see right but sinusoidal is asymmetric from power comparator, I have also with a offset with some other tests. but after a other feedback miltupole system it drops HD around -80 dB with 80 volts peak to peak in 8 ohms.
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Old 8th January 2017, 10:14 PM   #24
kees52 is offline kees52  Netherlands
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If I look to the simulations it looks like getting low distortion is not that difficult, -80dB 20 Khz and 80 volts Peak is not bad in 8 ohms, it looks like class D do keep it quite low over the whole bandwidth of the amp, in my case to 50Khz.

Multi pole fase shift do quite well, just one opamp and a power comparator do work, maybe a chip comparator who is faster can do even better but needs then a very fast power section, and power mosfets are not that fast because of gate capacity and needs a beefy driver to switch properly. however the power comparator do nice even above 1 Mhz, I use 800 Khz, I need bandwidth..

regards
Attached Images
File Type: jpg ScreenHunter_ Jan. 08 22.37.jpg (320.2 KB, 251 views)
File Type: jpg ScreenHunter_ Jan. 08 22.57.jpg (326.8 KB, 241 views)
File Type: jpg ScreenHunter_ Jan. 08 22.39.jpg (149.7 KB, 254 views)
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Old 9th January 2017, 07:41 AM   #25
Pafi is offline Pafi  Hungary
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Did you try what it does without load and for example with 1 kHz squarewave input?
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Old 9th January 2017, 12:33 PM   #26
kees52 is offline kees52  Netherlands
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Originally Posted by Pafi View Post
Did you try what it does without load and for example with 1 kHz squarewave input?
Njet


I do try keep in mind that a modulated carrier do NOT like squares because of harmonic intent, it is not a good
way of testing a D amp, only liniair amps can give info with it like ringing and such.

But I try what happens.

Hmm without load it do fine, very stable on carrier 800 Khz without load, however when I shut off audio it do not switch anymore
this it did also with load, putting just 0.001 volts it start again and is stable maybe it needs offset because I use the opa365
on 2 x 2.5 volts, this chip is max 5 volts single with ref..

Last edited by kees52; 9th January 2017 at 12:43 PM.
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Old 9th January 2017, 03:31 PM   #27
kees52 is offline kees52  Netherlands
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After calculate the coil the right way I get now tests with and without load incl a square wave (with and without load.)

Also the switching carrier to see it looks quite good, low distortion maybe because of multipole fase shift oscillator, it drops also less when near the rails.

regards
Attached Images
File Type: jpg ScreenHunter_ Jan. 09 15.28.jpg (234.6 KB, 226 views)
File Type: jpg ScreenHunter_ Jan. 09 15.29.jpg (256.6 KB, 208 views)
File Type: jpg ScreenHunter_ Jan. 09 15.33.jpg (239.9 KB, 43 views)
File Type: jpg ScreenHunter_ Jan. 09 15.37.jpg (232.5 KB, 40 views)
File Type: jpg ScreenHunter_ Jan. 09 15.38.jpg (258.9 KB, 43 views)
File Type: jpg ScreenHunter_ Jan. 09 15.58.jpg (315.9 KB, 40 views)

Last edited by kees52; 9th January 2017 at 03:34 PM.
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Old 9th January 2017, 04:31 PM   #28
Pafi is offline Pafi  Hungary
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Quote:
Originally Posted by kees52 View Post
Njet


I do try keep in mind that a modulated carrier do NOT like squares because of harmonic intent, it is not a good
way of testing a D amp,
The reason why square wave IS a good stimulation for testing is that it contains harmonics, this way you can check effectively at many frequencies at the same time.

(Not intent but content.)

Quote:
only liniair amps can give info with it like ringing and such.
Ringing and such can happen to any network, not only linear. I already shown this in the other thread.

Spelling: L-I-N-E-A-R! Please!

Quote:
But I try what happens.

Hmm without load it do fine, very stable on carrier 800 Khz without load, however when I shut off audio it do not switch anymore
this it did also with load, putting just 0.001 volts it start again and is stable maybe it needs offset because I use the opa365
on 2 x 2.5 volts, this chip is max 5 volts single with ref..
This can be the result of bad simulation setting also.

Doesn't switch? OK, but what it does?
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Old 9th January 2017, 10:49 PM   #29
kees52 is offline kees52  Netherlands
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Quote:
Originally Posted by Pafi View Post
The reason why square wave IS a good stimulation for testing is that it contains harmonics, this way you can check effectively at many frequencies at the same time.

(Not intent but content.)



Ringing and such can happen to any network, not only linear. I already shown this in the other thread.

Spelling: L-I-N-E-A-R! Please!



This can be the result of bad simulation setting also.

Doesn't switch? OK, but what it does?
What it does is just test it in real world, for the simulations, the settings are just reason that it did not right, special switching stuff is difficult to simulate, maybe Tina is better in it.

Yes I now I write everytime liniair, but must be lineair, but I am somebody who do not care much on spelling trouble.

Last picture you see what happens as someting is not set right in simulation, for special when get it faster, digital sims are slow, that is real world..

see some how low distortion it has, with extra poles in signal path as article did say, there is sooo much possible on the D amp technology, even coil less.

Ohh yes I say about the square that it in a coil do behave bad, I do most test 1 khz 10 kz 20 khz and see, a square is good for get lowest ringing and such, and yes in a amp it can also be, like in my circlotron design who go start again as parts arrive, but do not have them yet, so i play some with D amps, my friend the High End tube lover says class D do switch, that do never sound right, but now I get the drive to let him listen some day, maye I also do not like them, the circlotron allfet do sound very sweet and fast.

regards
Attached Images
File Type: jpg ScreenHunter_ Jan. 09 20.46.jpg (214.7 KB, 29 views)
File Type: jpg 1Khz.jpg (319.8 KB, 23 views)
File Type: jpg 50Khz.jpg (341.2 KB, 25 views)
File Type: jpg ScreenHunter_ Jan. 09 21.18.jpg (317.4 KB, 53 views)
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Old 10th January 2017, 05:47 AM   #30
Pafi is offline Pafi  Hungary
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You don't want to be easily understandable and got help, do you?
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