Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

how to do SC-CMFB for class AB output stage in 2-stage Fully differential opamp

Status
Not open for further replies.

prcken

Advanced Member level 1
Joined
Nov 1, 2006
Messages
419
Helped
41
Reputation
82
Reaction score
37
Trophy points
1,308
Location
Shanghai
Activity points
4,059
Hi, this topic was discussed before, it did show 5 threads when i typed the tilte.
here is one https://www.edaboard.com/threads/102298/

i almost used the same CMFB scheme as the last post for the class AB output stage, that is tuning the PMOS gate by adjusting the current into the output nodes. check the picture below
Capture.PNG
this works, especaily works good in continous time, but for Swtiched cap version, it doesn't work well, i think due to very low CMFB loop gain (less than 1.5 dB gain in my case) and in turn can cause very low bandwith (1.5MHz), the phase margin is extremly high since is a single pole system.

do you have any ideas or reference regarding this problem, how to do SC-CMFB for Class AB output stage?

Thanks!
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top