alternativ symmetric amp

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#4
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#5
It is patented by comlinear or is it National circa 1991 ?? I will have to take a look again. Used by Marantz in their top of the range.

It has excellent performance, wide bandwith with very high slewrate. Btw it is voltage VFB topology but it easily outperforms 99 % of all CFB topologies.

See Lm6172 as a example.
 
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#6
Had sketched this circuit on a rough piece of paper last night as I was having dinner and wanted to open a thread to discuss it and why it may be overkill 🙂 . The focus of this input stage involves Cob compensation, so cascodes are required on Q9 and Q11. Usually R1 is greater than R2 for valid reasons. You have also made it voltage feedback. Very nice. 🙂
 
#8
homemodder said:
Why would cascodes be required ?? They would then also be required on Q11 and Q12, the circuit is symmetric.
The bandwith and slewrate achievable with this circuit makes cascoding of little relevance.
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Q10 and Q12 yes. was talking about its native form. You will be surprised that this circuit if used as an audio amplifier rather than a video amplifier is easily beaten by a more elegant solution 🙂
 
#9
Yes, I is voltage feedback design. But I use a differential amplifier for controlling the current control and thus unite the advantages of both principles.
I've never seen a differential amplifier in which the signal was picked up at the emitter.
All circuits that you have shown me so far are similar except in the details of the differential amplifier.
But nice discussion so far 🙂
 
#10
OnAudio said:
Q10 and Q12 yes. was talking about its native form. You will be surprised that this circuit if used as an audio amplifier rather than a video amplifier is easily beaten by a more elegant solution 🙂
Click to expand...

Beaten in what why, performance ?? I very much doubt it.
If you are going to say the way it sounds, well Ill repeat a old Arab phrase (thanks to Wahab) here you wont like too much 😀
 
#15
Moschfet

I really like it, have something very similar in the works but at my rate I suspect 2014.

Elvee's thread "Is the CFB topology superior, and why?" led me to it but that thread has been somewhat up-rooted.

I have cascoded input transistors but for reasons of power dissipation and component selection flexibility.
Not that you need more gain but have you considered using those symmetrical collector currents from the feedback buffer?

Thanks and good Luck
-Antonio
 
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#16
Hi Antonio,

Not that you need more gain but have you considered using those symmetrical collectors from the feedback buffer?
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It's only a buffer. There is no voltage gain, so I don't need it. And it is going to grow too complicated with so many cascoded stuff...

I only want to publish my idea. Maybe someone can take parts of it or has a continuing idea.
 
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