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About step change in the output of SC circuits

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hr_rezaee

hr_rezaee

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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
 

maybe u should post the circuit and the test bench.
 

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.
 

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.
 

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
 

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.
 

    hr_rezaee

    hr_rezaee

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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
 

Thank

Added after 3 minutes:

0.52
 

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').
 

    hr_rezaee

    hr_rezaee

    Points: 2
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hr_rezaee said:
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
Click to expand...

you can refer to the op amp design.
 

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