when do we need to use CMFB?

Status
Not open for further replies.
K

knack

Member level 2
Joined
Feb 25, 2007
Messages
48
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,286
Location
Austria
Activity points
1,674
Hi there,
When designing a Diff. Pair amp., when should one use a CMFB ?
Thanks,
--Knack
 

You will need a CMFB circuit if u r designing a fully differential OpAmp, this is because you will two high impedance nodes and thus the dc level couldn't be maintained at a certain level
 

    K

    knack

    Points: 2
    Helpful Answer Positive Rating
eng_Semi said:
You will need a CMFB circuit if u r designing a fully differential OpAmp, this is because you will two high impedance nodes and thus the dc level couldn't be maintained at a certain level
Click to expand...

Sorry, I couldn't get what you said.
Please give more explanation,

Cheers,
--Knack
 


You can check the chapter of the fully differential amplifier from Razavi, it is very well explained
 

    K

    knack

    Points: 2
    Helpful Answer Positive Rating
CMFB is used to fix the output dc voltage level which comes from up and down currents mismatch.

and it can't be fixed through amplifier's negative feedback. so another feedback(CMFB) is used.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…