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https://designers-guide.org/forum/YaBB.pl Design >> Mixed-Signal Design >> Role of Dummy capacitors in SAR ADC https://designers-guide.org/forum/YaBB.pl?num=1404751069 Message started by eternity on Jul 7th, 2014, 9:37am |
Title: Role of Dummy capacitors in SAR ADC Post by eternity on Jul 7th, 2014, 9:37am Dear all, I just want to get clarified about the role of dummy capacitors in SAR ADCs. The dummy capacitor in the DAC array is used only for realising Vref quantities in terms of base-2 radix. or is it also used to realise some other functions too? Thanks to all Eternity |
Title: Re: Role of Dummy capacitors in SAR ADC Post by loose-electron on Jul 7th, 2014, 5:32pm Dummy devices are often used to serve as a similar perimeter device so all active devices exist in an identical environment. This often helps with component matching |
Title: Re: Role of Dummy capacitors in SAR ADC Post by eternity on Jul 8th, 2014, 2:51am Hi there thanks for the reply. I guess you interepreted my question in terms of layout I meant in terms of schematic. There is usually an extra unit cap placed in the DAC of SAR ADC to get binary weighed Vref levels(Vref/2, Vref/4..etc.,). I recently spotted in a journal seeing that extra cap connected to input voltage rather than to vref. So I want to get cleared on this. Thanks Eternity |
Title: Re: Role of Dummy capacitors in SAR ADC Post by loose-electron on Jul 8th, 2014, 12:03pm If it is on a reference voltage it could be for high frequency stability or reduction of coupling noise. |
Title: Re: Role of Dummy capacitors in SAR ADC Post by RobG on Jul 10th, 2014, 5:30pm eternity wrote on Jul 8th, 2014, 2:51am:
Interesting... which article had that? |
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