how to determine cap and switch sizes in SC CMFB ?

[jeffsky520]

looking forward to your reply.
Thanks and regards.

 

[sengyee88]

You may refer to CMFB chapter in the book
Analog IC Design, Ken Martin & David Johns

 

[mooner]

Thanks very much.
Where can i get it from, btw?

 

[sengyee88]

If IC design is your carrier, you will not regret of getting one.

 

[jeffsky520]

To SengYee88: I have look through that books, but no detail info for cap and switch size design. Look forwarding to your advise about that. Thanks anyway.

 

[sengyee88]

Hi,
You may refer to pg 291 of the book. Chapter 6.7 Current feedback opamps.
It is difficult to tell how much cap is needed, as it varies according to the opamp speed and current drive.

Basically, the SC form a R, that you would need to know how much R you need and hence design the C according to the SC theory.
h**p://www.swarthmore.edu/NatSci/echeeve1/Ref/FilterBkgrnd/SwitchedCap.html

Hope it helps.

 

[wonbef]

the selection of the size is related with bandwidth, noie, ...

 

[jeffsky520]

thanks to all.


1st warning!!!!!

 

[beckchm]

the ratio is 1/4 - 1/10