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-   -   Has anyone seen this front-end before? (http://www.diyaudio.com/forums/solid-state/209658-has-anyone-seen-front-end-before.html)

Edmond Stuart 27th March 2012 10:22 AM

Has anyone seen this front-end before?
 
1 Attachment(s)
To all,

Regarding the circuit as shown below, I like to know whether anyone has seen this front-end before. If so, I'm curious to learn more about it and how it behaves in real life. More details can be found here.
(BTW, I'm still editing and updating that page, so it's not yet finished)

Cheers,
E.

Osvaldo de Banfield 27th March 2012 12:33 PM

It is a complementary differential amplifier, but is drawing in a some curious way.

Edmond Stuart 27th March 2012 12:50 PM

>but is drawing in a some curious way
Why or which part?

Michael Chua 27th March 2012 01:36 PM

Haven't worked on this before but a very interesting design. Would I be right to say the 2nd stage current is set by the mirrors. If so, how precise must Q2 and Q3 be.

Am I seeing folded cascodes and cascodes in the 2nd stage?

Bonsai 27th March 2012 01:39 PM

I fail to see what this brings over more conventional approaches . . .

AndrewT 27th March 2012 01:41 PM

how do I1 & I2 get current from/to the supply rails?
The only route I can see is through the shorted CtoB of Q2 & 3

Edmond Stuart 27th March 2012 02:13 PM

Quote:

Originally Posted by Michael Chua (Post 2962077)
Haven't worked on this before but a very interesting design. Would I be right to say the 2nd stage current is set by the mirrors. If so, how precise must Q2 and Q3 be.

Hi Michael,

Yes, that right, but more precisely, Iq of the 2nd stage (the TIS) is defined by the tail current of the LTPs, which is reflected by the current mirrors.

Quote:

If so, how precise must Q2 and Q3 be.
Well, these transistors should be reasonably matched, just as with any other current mirror.

Quote:

Am I seeing folded cascodes and cascodes in the 2nd stage?
That's also correct, that is, the 'right legs' of the LTPs are 'folded', whereas the 'left legs' are connected via the current mirrors to the TIS.

Cheers,
E.

Bonsai 27th March 2012 02:16 PM

So What?

Edmond Stuart 27th March 2012 02:17 PM

Quote:

Originally Posted by Bonsai (Post 2962082)
I fail to see what this brings over more conventional approaches . . .

When I've finished the description on my website and you have read it, I hope you will understand the specific virtues of this circuit .

Cheers,
E.

overtheairbroadcast 27th March 2012 02:19 PM

Wow.

You guys are brilliant. Seriously, I just take a look and try to figure out how this works in a rudimentary way (out of interests sake and I have read those recommended books) and then you guys can disect and discuss it in no time flat.

Just something I noticed.


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