cross-quad and cascomp circuits - Page 2

rtarbell · 23rd September 2005, 07:28 AM

Thanks for all of your inputs! Let me ask, supose I were to make the cascomp in my input stage. I would make the regular differential pair with about 5mA of tail current and an active load to the VAS stage. For the inner differential pair (the cascomp circuit itself), is there any rule of thumb as to what its tail current should be?

thanh · 10th April 2007, 09:47 AM

Quote:

Also the book "Analog Circuit Design", edited by Jim Williams and published by EDN, has two chapters by John Addis and Barrie Gilbert that might help answer your question

Hi Tom2! I have not got it. Can you summarize those chapters? I want to know reason.
Does Distortion decrease by local feedback or global feedback?
Does this techique have any improvement in a whole amp ? or Is it good when do analysing the only input stage ?
Thanks !

darkfenriz · 31st August 2007, 01:28 AM

Hi

What is the main difference between multi tanh stage and so-called 'schmook pair' ?? the basic idea seems similar to me... has Gilbert re-invented what Schmook had before

Steven · 31st August 2007, 06:48 PM

They seem to be the same, at least for the case 1:n and n:1 cross-connected.

See patent 5933054: http://www.freepatentsonline.com/5933054.pdf
From this patent:

" An example of the conventional bipolar OTAs was disclosed by Schmook in the IEEE Journal of Solid-State Circuits, Vol. SC-10, No. 6, PP. 407-411, December 1975, in which two unbalanced differential pairs of bipolar transistors are employed. Two transistors of each pair has different emitter areas or sizes. Output ends or collectors of the two transistors of each pair are cross-coupled.

The transconductance linearization technique proposed by Schmook is known as the "Multi-tanh" technique, and has been practically used.

An application of this Multi-tanh technique was disclosed y Tanimoto et al., in IEEE Journal of Solid-State Circuits, Vol. 26, No. 7, PP. 937-945, July 1991."

This patent mentions an alternative approach to linearization.

Steven · 31st August 2007, 06:52 PM

At least Gilbert mentions Schmook in his paper, (Reference 4).
See #3.

darkfenriz · 1st September 2007, 03:09 PM

So Schmook's pair is multi tanh.
That's funny, I used to think it's Gilbert's invention.
However Gilbert's article is great in terms of analysis and popularisation.

31st August 2007, 01:28 AM	#13
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	Multi Tanh Hi What is the main difference between multi tanh stage and so-called 'schmook pair' ?? the basic idea seems similar to me... has Gilbert re-invented what Schmook had before

31st August 2007, 06:48 PM	#14
Steven diyAudio Member Join Date: Oct 2003 Location: The Netherlands	Schmook They seem to be the same, at least for the case 1:n and n:1 cross-connected. See patent 5933054: http://www.freepatentsonline.com/5933054.pdf From this patent: " An example of the conventional bipolar OTAs was disclosed by Schmook in the IEEE Journal of Solid-State Circuits, Vol. SC-10, No. 6, PP. 407-411, December 1975, in which two unbalanced differential pairs of bipolar transistors are employed. Two transistors of each pair has different emitter areas or sizes. Output ends or collectors of the two transistors of each pair are cross-coupled. The transconductance linearization technique proposed by Schmook is known as the "Multi-tanh" technique, and has been practically used. An application of this Multi-tanh technique was disclosed y Tanimoto et al., in IEEE Journal of Solid-State Circuits, Vol. 26, No. 7, PP. 937-945, July 1991." This patent mentions an alternative approach to linearization. __________________ The Analog Art shows no sign of yielding to the Dodo's fate. The emergence and maturation of monolithic processing finesse has perhaps lagged a bit behind the growth of the Binary Business. But whereas digital precision is forever bounded by bits, there is no limit excepting Universal Hiss to the ultimate accuracy and functional variety of simple analog circuits. - Barry Gilbert, 1973

31st August 2007, 06:52 PM	#15
Steven diyAudio Member Join Date: Oct 2003 Location: The Netherlands	Schmook and Gilbert At least Gilbert mentions Schmook in his paper, (Reference 4). See #3. __________________ The Analog Art shows no sign of yielding to the Dodo's fate. The emergence and maturation of monolithic processing finesse has perhaps lagged a bit behind the growth of the Binary Business. But whereas digital precision is forever bounded by bits, there is no limit excepting Universal Hiss to the ultimate accuracy and functional variety of simple analog circuits. - Barry Gilbert, 1973

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23rd September 2005, 07:28 AM	#11
rtarbell diyAudio Member Join Date: Sep 2005	Thanks for all of your inputs! Let me ask, supose I were to make the cascomp in my input stage. I would make the regular differential pair with about 5mA of tail current and an active load to the VAS stage. For the inner differential pair (the cascomp circuit itself), is there any rule of thumb as to what its tail current should be?

1st September 2007, 03:09 PM	#16
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	So Schmook's pair is multi tanh. That's funny, I used to think it's Gilbert's invention. However Gilbert's article is great in terms of analysis and popularisation.

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