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Top plate sampling VS bottom plate sampling in SAR ADC (Read 7881 times)

kollayliu Junior Member Offline Posts: 22	Top plate sampling VS bottom plate sampling in SAR ADC Feb 13^th, 2013, 8:43am Hi all, In SAR ADC, one advantage of top plate sampling over bottom plate sampling is that the number of unit capacitors of the former is only the half of the latter. What's the reason for that? Thanks in advance.
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RobG Community Fellow Offline Posts: 570 Bozeman, MT	Re: Top plate sampling VS bottom plate sampling in SAR ADC Reply #1 - Feb 23^rd, 2013, 1:36pm I don't think it has anything to do with top or bottom plate. You'll have to post the schematics so we can figure out why they are different.
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Morph19

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Re: Top plate sampling VS bottom plate sampling in SAR ADC
Reply #2 - Mar 14^th, 2013, 8:05am

Its because in top plate sampling you have the inputs signals in the inputs of the comparator after the sample period. In bottom plate you have to sample the input in all the capacitor and next start the switching procedure lets say by connecting the MSB capcitor to Vref and the rest to ground, but sine in top plate sampling you already have the inputs in the comparator from the begining you dont need that MSB capacitor anymore.

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kollayliu Junior Member Offline Posts: 22	Re: Top plate sampling VS bottom plate sampling in SAR ADC Reply #3 - Mar 22^nd, 2013, 4:24pm Dear RobG and Morph19, thanks for your reply. Your reply helped me figured it out.
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