The Designer's Guide Community
Forum
ForumVerilog-AMSAnalysisModelingDesignTheory
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Jul 29th, 2024, 5:10am
 
  HomeHelpSearchLoginRegisterPM to admin    
The Designer's Guide Community Forum › Design › Analog Design › 3.3V opamp design with 1.8V devices
‹ Previous topic | Next topic ›
Pages: 1
Send Topic Print
3.3V opamp design with 1.8V devices (Read 3344 times)
rampat
Junior Member
**
Offline



Posts: 14
3.3V opamp design with 1.8V devices
Dec 27th, 2010, 5:06am  
Hi All

I need to design a  opamp with 3.3V supply and only 1.8V devices are available from the process.How to take care of the reliability issues for the devices? If anyone knows solutions or  any reference/papers  to the above problem it will be a great help.


Thanks
rampat
Back to top
 
 
View Profile rampat   IP Logged
rfmagic
Community Member
***
Offline



Posts: 64
Re: 3.3V opamp design with 1.8V devices
Reply #1 - Dec 27th, 2010, 7:29am  
Telescopic configurationד seems the right choice for you as each transistor will take on some of the voltage to lower the stress form the 1.8V devices. On top of that you can get more gain due to the increased ouput impedances of the stacked stages.
Back to top
 
 
View Profile   IP Logged
AnalogDE
Senior Member
****
Offline



Posts: 137
Re: 3.3V opamp design with 1.8V devices
Reply #2 - Dec 30th, 2010, 1:22am  
You may also want to look into using a level shifter or regulator to level shift the supply down to around 1.8V.
Back to top
 
 
View Profile   IP Logged
nus_lin
Community Member
***
Offline



Posts: 48
Re: 3.3V opamp design with 1.8V devices
Reply #3 - Jan 15th, 2011, 7:02pm  
the key point here is to design your circuit and set proper operation condition so that none of the Vgs or Vgd exceeds 1.8V, because the gate oxide is the most vunerable part. for diodes, the breakdown voltage should be larger than 3.3.
Back to top
 
 
View Profile   IP Logged
HdrChopper
Community Fellow
*****
Offline



Posts: 493
Re: 3.3V opamp design with 1.8V devices
Reply #4 - Jan 17th, 2011, 4:47pm  
As rfmagic suggested cascodes are the way to go, always taking care of not creating VGs voltages higher than 1.8v.
That way the 3.3v max operating voltage will be always split among at least to devices in series.

Best
Tosei
Back to top
 
 
Keep it simple
View Profile   IP Logged
Pages: 1
Send Topic Print
‹ Previous topic | Next topic ›
« Home ‹ Board
The Designer's Guide Community Forum » Powered by YaBB 2.2.2!
YaBB © 2000-2008. All Rights Reserved.
Copyright 2002-2024 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.