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minxin_zhou
Joined: 17 Nov 2004
Posts: 12
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 30 Dec 2004 15:47 KT/C noise of switch in switched capacitor circuits |
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| Can anybody tell me why the KT/C noise induced by switches in switched capacitor circuits can be eliminated by differencial configuration? It is well known that the offset and 1/f noise can be eliminated by CDS(corelated double sampling) technique. But why this noise can also be cancelled?
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markty
Joined: 15 Dec 2004
Posts: 60
Helped: 2
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| 30 Dec 2004 17:04 KT/C noise of switch in switched capacitor circuits |
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I do not think those noise can be eliminated.
Differential structure give good psrr and suppress common mode noise.
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borodenkov
Joined: 02 Mar 2004
Posts: 129
Helped: 11
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| 31 Dec 2004 0:34 KT/C noise of switch in switched capacitor circuits |
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| differential configuration will not reduce kT/C noise
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bastos4321
Joined: 01 Jan 1970
Posts: 334
Helped: 24
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| 31 Dec 2004 0:35 Re: KT/C noise of switch in switched capacitor circuits |
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| minxin_zhou wrote: |
| Can anybody tell me why the KT/C noise induced by switches in switched capacitor circuits can be eliminated by differencial configuration? It is well known that the offset and 1/f noise can be eliminated by CDS(corelated double sampling) technique. But why this noise can also be cancelled? |
The thermal noise is not eliminated by using differencial configuration. It is allways there. You can only increase the capacitor to make it lower of using a lower signal bandwith.
Bastos
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minxin_zhou
Joined: 17 Nov 2004
Posts: 12
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| 31 Dec 2004 4:41 Re: KT/C noise of switch in switched capacitor circuits |
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I found in some literatures that the KT/C noise induced by switches can also been first orderly cancelled using the CDS technique. I am confused with that conclusion since I think the thermal can not be eliminated. The reference is below:
http://168.160.16.198/umi/document?RecordNo=1&ColumnName=Pdf_name&MultiNo=0&issource=yes&type=bin&isdownload=yes&searchword=t_title%3Dcapacitive+sensor+interface&singlesearch=no&channelid=%CF%B8%C0%C0
Please see page NO.12.
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nxing
Joined: 10 May 2004
Posts: 446
Helped: 12
Location: China
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| 03 Jan 2005 3:12 KT/C noise of switch in switched capacitor circuits |
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| The link doesn't work.
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totoro
Joined: 27 Jun 2004
Posts: 84
Helped: 10
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| 04 Jan 2005 9:03 Re: KT/C noise of switch in switched capacitor circuits |
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| of course can not
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reltol1
Joined: 15 Dec 2004
Posts: 19
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| 04 Jan 2005 10:17 Re: KT/C noise of switch in switched capacitor circuits |
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| diffrential configuration sometimes boubles kt/C noise, never reduce.
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terryssw
Joined: 18 Apr 2004
Posts: 176
Helped: 14
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| 06 Jan 2005 14:29 Re: KT/C noise of switch in switched capacitor circuits |
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| kT/C noise power will double using differential structure, but the voltage swing will be double also thus induced 4x in signal power, so SNR improved by 3 dB compared to single-ended one.
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