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.

Register Log in

Fully Differential Opamp - Folded Cascode + Common Source SC CMFB Issues

Status
Not open for further replies.
P

Puppet123

Full Member level 6
Joined
Apr 26, 2017
Messages
356
Helped
22
Reputation
44
Reaction score
21
Trophy points
18
Activity points
3,059
Hello,

I have designed a two stage opamp - one stage is a folded cascode opamp followed by a common source stage - I am using a 65 nm process and need the extra gain of the common source stage.

I want to use SC CMFB for each stage. What are the timing issues for doing this with these two stages? What should I keep in mind or look out for? Any resources on this set up? Any advice on the timing and clocking?

Thanks.
 

You can use the same clock for both of the stages if they are both fully differential. In this case, you may need 10-15 clock cycles to set up the desired common mode. This is dependent on the SC CMFB switches and used caps (their time constant). In these settling clock cycles you cannot sample the output acccurately. So smaller caps and large switches are beneficial.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top