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[help] dc offset cancellation techniques (Read 6665 times)

trashbox Community Member Offline Posts: 66	[help] dc offset cancellation techniques Dec 08^th, 2009, 2:14am Hi all, As attachment, the class-AB driver output is audio signal (20~20KHz) and has 1~10mV DC offset. Is there any method or close-loop DC offset cancellation circuit to eliminated it(spec. require the dc offset <2mV)? Can the so-called servo circuit solve this problem in this case? Thanks in advance. Regards
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duncandu New Member Offline Posts: 6	Re: [help] dc offset cancellation techniques Reply #1 - Dec 8^th, 2009, 1:40pm Like auto-zero, or servo DAC, etc. Many techniques on offset cancellation can be applied in this case.
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trashbox Community Member Offline Posts: 66	Re: [help] dc offset cancellation techniques Reply #2 - Dec 8^th, 2009, 5:56pm Hi duncandu, Thanks for your reply. Would you please offer me the servo DAC references? Best regards
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HdrChopper Community Fellow Offline Posts: 493	Re: [help] dc offset cancellation techniques Reply #3 - Dec 8^th, 2009, 6:32pm Hi Trashbox, Check this thread for references on choppers for SE amplifiers... http://www.designers-guide.org/Forum/YaBB.pl?num=1259664512 Best Tosei
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RobG

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Bozeman, MT

Re: [help] dc offset cancellation techniques
Reply #4 - Dec 14^th, 2009, 5:05pm

I'm not sure why you are seeing such offset in simulation - are you sure it isn't a finite gain issue? At any rate, if you are using a process 0.5u or smaller you should easily be able to get the offset down by using larger devices. You probably want low 1/f anyway. Chopping might also work well since the input frequency is low, and the ear is a great filter above 20kHz

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