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Jonathan Harris

Interleaving Spurs: The Mathmatics of Timing Mismatch

Jonathan Harris
jonharris0
jonharris0
10/28/2013 8:44:27 AM
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Blogger
Re: Re : Interleaving Spurs: The Mathmatics of Timing Mismatch
Thanks for the comments yalanand.  You are correct, probably the simplest interleaving mismatch to look at is the offset mismatch.  I've discussed that here http://www.planetanalog.com/author.asp?section_id=3041&doc_id=560484 and here http://www.planetanalog.com/author.asp?section_id=3041&doc_id=561191

Definitely appreciate all these comments from everyone, please keep them coming! :-)

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yalanand
yalanand
10/27/2013 7:14:26 AM
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Newbie
Re : Interleaving Spurs: The Mathmatics of Timing Mismatch
Probably the calmest of these to realize is the offset disparity between the two ADCs.  Each ADC would have a related DC offset value. When the two ADCs are enclosed and samples are learned alternatively back and forth among the two ADCs, the DC offset of each consecutive sample is altering. 

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jonharris0
jonharris0
10/18/2013 8:20:35 AM
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Blogger
Re: Timing
Hi Sunita, thanks for the comment. You are correct, typically SFDR is defined by the fundamenatl and the most prominent harmonic. In the case of the interleaved ADC, with enough mismatch, the interleaving spur can be significantly higher than the highest harmonic.  In this case, it drives what the actual SFDR is since the dynamic range is then typically limited by the amplitude of the interleaving spur.

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samicksha
samicksha
10/10/2013 6:22:57 AM
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Student
Timing
Mathematics has always been a nightmare for, but if we refer SFDR it is between the amplitude of the frequency being generated and the amplitude of the most prominent harmonic.

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More Blogs from Jonathan Harris
We begin this series of blogs by taking a look at ADIsimADC, which is a quite relevant design tool for Jonathan Harris, an applications engineer in ADI's high-speed ADC group.
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.
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