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.

Simple CMFB using two transistors only

Status
Not open for further replies.

Junus2012

Advanced Member level 5
Joined
Jan 9, 2012
Messages
1,552
Helped
47
Reputation
98
Reaction score
53
Trophy points
1,328
Location
Italy
Activity points
15,235
Dear friends,

I see some people are using the CMFB presented in the circuit below (transistor M3 and M4 with the VCM connection), it looks very simple but I don't know why it is not very known like other standard circuit.
Can you explain me please the work princible of it ?

thanks

CMFB.PNG
 

It seems extremely mismatch sensitive. The size or threshold difference generated error of the added devices is amplified by the folded cascode stage, I think it is not a practically viable solution.
 
It seems extremely mismatch sensitive. The size or threshold difference generated error of the added devices is amplified by the folded cascode stage, I think it is not a practically viable solution.

Me also I think is not practical solution otherwise people would follow it as it looks very simple,,, but still some of them are following like in book of operational ampliifer theory and design by Johan Huijsing
 

by the way I found the explanation from the boook as shown below with the circuit,

He put a condition to use this circuit if the amplifier has DC positive CM feedback, this status I didn't understand, how can I know it from my amplifier ?

huj1.PNG

huj2.PNG
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top