[SOLVED] Gain booster biasing circuitry

[mordak]

Hi,

I designed a folded cascode opamp with gain boosting and it works properly, now I want to design biasing voltages of the opamp. I could design a biasing circuitry for the main opamp, but I had a hard time finding a way to generate the dc voltages that need to be applied to the gain booster input. I mean, I found the values in the first step of the design and now want to generate those voltages using transistors (say NBIAS1 in the pic), and I wonder if I can make them with the circuit I am using as biasing circuit for the main opamp/gain booster, or not. Hope someone help me figure it out.

P.s: found this pic on edaboard and didn't draw it myself, besides it is not folded cascode, just wanted to show which voltage I was talking about.

 

[tgootee]

You say, "I wonder if I can make them with the circuit I am using as biasing circuit for the main opamp/gain booster, or not."

What circuit is that?!

Please post _YOUR_ actual schematic, that you have so far.

 

[mordak]

What circuit is that?!

Please post _YOUR_ actual schematic, that you have so far.

Tnx for your reply. Actually I've not drawn that yet using visio or other softwares like that. But I'm using biasing circuitry found in Jones and Martin. That part is totally straight forward, however, I couldn't find any book, paper, thesis .... which describes biasing circuitry for the gain boosting part (I mean the voltage you apply to the input: NBIAS1), so I'm kinda confused, how that voltage could be generated.