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hr_rezaee
Joined: 06 Oct 2004
Posts: 869
Helped: 88
Location: Iran-Mashhad
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 01 Jan 2008 8:52 About step change in the output of SC circuits |
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Dear All
Hi
I need some papers or books about step change in the output of SC circuit (for example MDAC of pipeline ADC) in the direction of opposite to its final value.
I need proof of it.
regards
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safwatonline
Joined: 19 Nov 2005
Posts: 1368
Helped: 163
Location: EGYPT
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| 01 Jan 2008 9:06 About step change in the output of SC circuits |
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| maybe u should post the circuit and the test bench.
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hr_rezaee
Joined: 06 Oct 2004
Posts: 869
Helped: 88
Location: Iran-Mashhad
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| 01 Jan 2008 9:20 Re: About step change in the output of SC circuits |
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Hi
Thanks
I mean theoretical proof for step change in the output of SC circuits.
I have one in this paper but I need better one.
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mitgrace
Joined: 08 May 2004
Posts: 334
Helped: 4
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| 05 Jan 2008 4:17 Re: About step change in the output of SC circuits |
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Dear Sir :
What is your mean ? the S.C output is evaluation. You must see DAC output (reference circuit) , it is settling . The almoset key is here. But there are few papers discuss it.
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hr_rezaee
Joined: 06 Oct 2004
Posts: 869
Helped: 88
Location: Iran-Mashhad
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| 05 Jan 2008 7:59 Re: About step change in the output of SC circuits |
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Hi
there is an proof for step changes at the start of charge transfer phase in some SC circuits such as SC amplifier.
see these figs and above attached paper.
Now, I need another paper or book that discaused about this phenomenon.
I need better mathematical proof for it.
best regards
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lladnar23
Joined: 20 Mar 2006
Posts: 200
Helped: 27
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| 05 Jan 2008 23:15 About step change in the output of SC circuits |
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| Yea, so it's just a capacitive divider involving the feedback capacitor (CF) and the load capacitor (CL). Let me illustrate with a simple example. Consider an inverting stage with a gain of -2, and your feedback capacitor is 1/10 the size of your load capacitor. Now lets say we apply a -1V step input. There are two things that occur. First, we have a step change at the output due to the capacitive divider CF/CL. The output sees a negative step of Vin*CF/CL. For our numbers that's -1V*1/10 = -0.1V. Next, we have the settling of the stage, and it will settle to 2*Vin = +2V. So you can see that initially the output goes negative, then it eventually settles to the positive value as we expected.
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hr_rezaee
Joined: 06 Oct 2004
Posts: 869
Helped: 88
Location: Iran-Mashhad
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| 06 Jan 2008 22:18 About step change in the output of SC circuits |
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Dear lladnar23
Thanks
It is true. but I can't understand why we use step as input?
can you explain about step input in for example S/H circuit or Gain stage ?
Best regards
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zawmintun1
Joined: 21 Nov 2007
Posts: 44
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| 08 Feb 2008 12:55 About step change in the output of SC circuits |
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Thank
Added after 3 minutes:
0.52
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lladnar23
Joined: 20 Mar 2006
Posts: 200
Helped: 27
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| 09 Feb 2008 4:51 About step change in the output of SC circuits |
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| Well, since it's a switched capacitor circuit, we are sampling some voltage in clock phase 1, then when clock phase 2 happens, we apply the sampling cap to the virtual ground node of the opamp -- that's basically a step change in voltage since the voltage on a cap can't change instantaneously (I=CV').
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northeast1
Joined: 21 Jun 2007
Posts: 150
Helped: 4
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| 13 May 2008 9:52 Re: About step change in the output of SC circuits |
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| hr_rezaee wrote: |
Dear All
Hi
I need some papers or books about step change in the output of SC circuit (for example MDAC of pipeline ADC) in the direction of opposite to its final value.
I need proof of it.
regards |
you can refer to the op amp design.
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