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Design >> Analog Design >> self biased opamp in LDO
https://designers-guide.org/forum/YaBB.pl?num=1147090006

Message started by grosser on May 8^th, 2006, 5:06am

Title: self biased opamp in LDO
Post by grosser on May 8^th, 2006, 5:06am

hello

could you tell me how to design a startup circuit in attached schematic?

bias current depends on load current. without startup circuit M0 goes into cutt-off

regards

Title: Re: self biased opamp in LDO
Post by zhonghan on May 11^th, 2006, 2:00am

in attachment is my reply ,all scales of transistors are not correct .

Title: Re: self biased opamp in LDO
Post by grosser on May 12^th, 2006, 2:38pm

how is the opamp's bias current set?
M3's drain voltage is set to Mout give wanted load? this drain voltage determines M3's current andso on??

what if load current IL is small?

regards

Title: Re: self biased opamp in LDO
Post by ywguo on May 15^th, 2006, 6:30pm

Hi, Grosser,

There are many descriptions about start-up circuits in some textbooks. I think they could be used in your self-biased opamp. Please select one book in Designer's Guide Book List.

http://www.designers-guide.org/Books/

Best regards,
Yawei