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Negative feedback - right or wrong to use?
Negative feedback - right or wrong to use?
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Old 24th February 2018, 05:19 AM   #91
globalplayer is offline globalplayer  Germany
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LOL!
OK.
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Old 24th February 2018, 06:43 AM   #92
AllenB is offline AllenB  Australia
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My best wishes to Frau Global
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Old 24th February 2018, 10:05 AM   #93
Mikelandjelo is offline Mikelandjelo  Serbia
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Quote:
Originally Posted by elukacs View Post
Hi Nigel,

check TAS5614A power stage data sheet. Due to the internal compensation it has
80 dB PSSR.
Furthermore it is a BTL design which lowers supply rail pumping.

PS: datasheet http://www.ti.com/lit/ds/symlink/tas5614a.pdf

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Old 24th February 2018, 10:20 AM   #94
scottjoplin is offline scottjoplin  Wales
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Originally Posted by Davey View Post
So God selected you for this revelatory improvement to amplifier design, but told you not to say anything about it?
I guess God is laughing at all of us poor souls...through you?

What a pathetic thread.

Dave.
Ironically, He was big on negative feedback
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Old 24th February 2018, 03:30 PM   #95
MarcelvdG is online now MarcelvdG  Netherlands
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Quote:
Originally Posted by elukacs View Post
Hi Nigel,

check TAS5614A power stage data sheet. Due to the internal compensation it has
80 dB PSSR.
Furthermore it is a BTL design which lowers supply rail pumping.

PS: datasheet http://www.ti.com/lit/ds/symlink/tas5614a.pdf
The functional block diagram depicts a feedback loop of unknown order for each of the four output stages.
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Old 24th February 2018, 03:45 PM   #96
Fast Eddie D is offline Fast Eddie D  United States
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Quote:
Originally Posted by MarcelvdG View Post
The functional block diagram depicts a feedback loop of unknown order for each of the four output stages.
From the data sheet.

Quote:
The TAS5614A is a high performance digital input class D amplifier with integrated closed loop feedback technology.


The problem with lying to engineers about engineering topics is that we can read the datasheet. We're not gullible consumers of the products. We design the products!

Nice try though.
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Old 24th February 2018, 04:20 PM   #97
elukacs is offline elukacs  Hungary
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Yes, I wrote this part has some unknown local feedback inside.

But who cares if the result is good, the PWM generation process is out of this feedback,
and on the design level you don't have to deal with analog problems from the speaker
port to the input of pwm gen. You can see it as fb less solution with good enough driver stage.
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Old 24th February 2018, 04:28 PM   #98
MarcelvdG is online now MarcelvdG  Netherlands
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In the context of this thread, I expect everyone cares about it (except you, apparently). I'm really curious why TI chose such a weird solution, with open-loop PWM generation followed by an N-th order analogue feedback loop.
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Old 24th February 2018, 05:05 PM   #99
elukacs is offline elukacs  Hungary
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TI: Earlier they made open loop driver stages only. Then probably they realized that
with some compensation they can improve on timing of FETs and PSSR.
I would be surprised if that is a complex Nth order loop.

I think the point here is that they splitted the problem into PWM generation in digital domain, and making good enough driver stage. The former is limited only by the DSP and its clock source.
The later can be improved as FET technology improves.
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Old 24th February 2018, 08:42 PM   #100
globalplayer is offline globalplayer  Germany
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Originally Posted by AllenB View Post
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