A linear transconductance for OTA-C filter

[afujian]

I just don't understand why the parallel differencial pair can increase the linearity of the OTA, who can tell me why?

 

[LvW]

When you say "increase" you compare the linearity of two different concepts. Therefore: What is the other design (with smaller linearity) ?

 

[wpchan05]

it is a technique of multi-tanh for bipolar linear transconductor.

 

[erikl]

... why the parallel differencial pair can increase the linearity of the OTA?

Because of the summing of 2 currents from 2 pairs with slightly different - yet controlled - offset voltages (due to the K ratio). Works correctly only with BJTs or MOSFETs in weak inversion. See the visualization in the PDF below:
View attachment multi-tanh-linearization.pdf

 

[afujian]

I am sorry about the cofusion,I am comparing the singal differencial pair such as Q10 and Q11.

 

[FvM]

Q10/Q11 isn't a differential pair. Please notice that they are operating on two separate current sources. I think, the explanation in the linked paper is rather graphic.

 

[afujian]

Q10/Q11 isn't a differential pair. Please notice that they are operating on two separate current sources. I think, the explanation in the linked paper is rather graphic.

OK,I mean to compare with the single differential pair.