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Jonathan Harris

How Do You Analyze ADC Noise? Part 2

Jonathan Harris
jonharris0
jonharris0
2/3/2014 10:14:06 AM
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Re: frequency sweep
Again, very good point.  The discrepancies are small in this case compared with the magnitude of the measurement.  Thanks to you for the kind words.  I enjoy the questions and interactions.  Thanks!

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etnapowers
etnapowers
2/3/2014 10:05:52 AM
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Re: frequency sweep
@Jonathan: thank you for this post, the small discrepancies are for sure due to this cause, however if the discrepancies with the actual measured data are small compared to the expected order of magnitude of the measurement, the approximation is valid.

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jonharris0
jonharris0
1/13/2014 4:06:20 PM
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Re: frequency sweep
Indeed, good points.  The ideal nature of the calculations does lend itself to some small discrepancies with the actual measured data.  I am always happy when measured data lines up closely with my calculated values. :-)

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etnapowers
etnapowers
12/28/2013 3:33:22 AM
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Newbie
frequency sweep
I wonder if the error between theoretical and measured ADC noise depends on the frequency, due to capacitive or inductive effects that may appear as the operating frequency varies.

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etnapowers
etnapowers
12/28/2013 3:27:21 AM
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relative error
I think that an engineer has to take care of the absolute and relative error when evaluating theoretically a ADC noise and then measuring it.

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More Blogs from Jonathan Harris
In this blog we’ll take this one step further and look at driving the ADC power supplies directly from a DC/DC converter.
Previously in this blog series we looked at using a DC/DC converter (switching regulator) in combination with an LDO to drive the power supply inputs to an ADC. What we found was that using the DC/DC converter to step down the input voltage for the LDO was a much more efficient way to drive the power supply inputs to an ADC.
We look at using a DC/DC converter along with an LDO to drive the ADC power supply inputs.
I thought it would be good to continue looking at the example I gave in my last blog where we looked using fewer LDOs and combining power supply rails on an ADC while maintaining isolation with ferrite beads.
There are some disadvantages when driving low input supply voltages, where multiple LDOs may be required.
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