noise in switch cap circuit

[dejunwang]

hi, I have a question regarding noise in general. Say I have a cap of value 4C. then I have a total KT/C noise of KT/4C. Then if I use 4 identical caps of value C each and a switch in each branch, then the total noise is still KT/4C? It is quite hard to visualize as at the moment when the switches are open, each cap has a Vnoise equal to KT/C stored on the top plate. When you sum them up in power, wouldn't they become 4*KT/C?


I know this might be a silly question but I am really confused at the point.


thanks for the help.

 

[winsonpku]

I advise you read cha7 of razavi's book.
you will get clear on this issue

hi, I have a question regarding noise in general. Say I have a cap of value 4C. then I have a total KT/C noise of KT/4C. Then if I use 4 identical caps of value C each and a switch in each branch, then the total noise is still KT/4C? It is quite hard to visualize as at the moment when the switches are open, each cap has a Vnoise equal to KT/C stored on the top plate. When you sum them up in power, wouldn't they become 4*KT/C?


I know this might be a silly question but I am really confused at the point.


thanks for the help.

 

[mkhafaji]

because the noise are power not voltage or current and also several sources may not be uncorrelated they are not added in the way that we think about them.