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Design >> Mixed-Signal Design >> Splitting the Cap would increse the thermal noise ??
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Message started by jefkat on Dec 30^th, 2010, 10:11am

Title: Splitting the Cap would increse the thermal noise ??
Post by jefkat on Dec 30^th, 2010, 10:11am

Hi Guys,
If I have a switched cap integrator and I split its input sampling cap into two equal halves (see the attachement). Would the equivalent input thermal noise (KT/C) double aswell? In my opinion it should double because both caps are independantly sampling or I missed something.
Please have a look at this jpg that shows what I am asking.
Thanks for the answers.
shaf

Title: Re: Splitting the Cap would increse the thermal noise ??
Post by ssahl on Jan 2^nd, 2011, 7:22am

The total noise will not double. For each capacitor it will. But your circuit will add the noise currents from the two input capacitors and the sum will be equal to the one comming from the only one capacitor case.