The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Analog Design >> CMFB Desing Question
https://designers-guide.org/forum/YaBB.pl?num=1336913838

Message started by Analog_Designer on May 13^th, 2012, 5:57am

Title: CMFB Desing Question
Post by Analog_Designer on May 13^th, 2012, 5:57am

I'm working on a Capacitive Feedback Telescopic Cascode OTA Design using 0.35 um technology and i can't design a CMFB without deteriorating the output swing as the Dynamic range is one of the major concerns . any suggestions ? ..... Thanks in Advance .....

Title: More details
Post by Analog_Designer on May 14^th, 2012, 1:55am

Okay then ! This was my first question in this forum hoping for the people to interact more than this . Any way the topologies i tried till now are three. the attached file may explain it better than me ... :D . I hope this time i get an answer .... thanks in advance .....

Title: Re: CMFB Desing Question
Post by Lex on May 14^th, 2012, 4:10am

Are you really expecting us to help you with something that resembles a homework assignment? ;)

Some hints:
- if your swing is a problem, check voltage headroom, and determine what is limiting the voltage headroom.
- if your voltage headroom is the problem, apply some topology that is best for it. Make a good mix and match of NMOS and PMOS. =)

Good luck.

Title: Re: CMFB Desing Question
Post by Analog_Designer on May 14^th, 2012, 12:44pm

Lex wrote on May 14^th, 2012, 4:10am:

First: Thank you for your reply

Second : I just need help in my way of learning analog design, by the way i have just been graduated from the faculty of engineering, Electronics and Communication Department in 2011 ,means i'm a fresh graduate, and i'm ,now, working as a VLSI Researcher in a research lab ,just started, i have taken this project to learn and to revise the analog info i have taken in the college and to put them in action ,so, i thought of interacting with people in a forum so as to exchange knowledge and experiences . thank you anyway :)

Title: Re: CMFB Desing Question
Post by wave on May 14^th, 2012, 5:43pm

Look at a Switched Cap CMFB circuit

Title: Re: CMFB Desing Question
Post by ywguo on May 16^th, 2012, 2:37am

The output voltages of OTA are out of the normal operating range of your two CMFB circuits.

Yawei