Design Con 2015
Home    Bloggers    Blogs    Article Archives    Messages    About Us   
Tw  |  Fb  |  In  |  Rss
Jonathan Harris

Interleaving Spurs: Offset Mismatches

Jonathan Harris
jonharris0
jonharris0
7/15/2013 9:10:59 AM
User Rank
Blogger
Re: Calibration / DC components
@DaeJ, thanks for the question.  The figure is intended just to show that the offset mismatch exists.  It is not necessarily a calibration circuit, sorry for the confusion on that.

@B_Albing, thanks for the comment as well...that is something good to keep in mind.  I'm hoping to dive into a few more of the mismatches in upcoming blogs, but perhaps a good direction afterward may be to discuss some calibration methods...

50%
50%
B_Albing
B_Albing
7/15/2013 12:17:57 AM
User Rank
Editor
Re: Calibration / DC components
@JH - more details on auto-cal methods to remove (or match) DC offset in a future blog, perhaps....

50%
50%
DaeJ
DaeJ
7/14/2013 5:35:02 PM
User Rank
Master
Two ADADC71 chips
I think that in most case, A/D converter chip is used to get A/D from VIN in the circuit. For example, let us say that two ADADC71 chips, 16 bit A/D converter, are used in parallel similar to "Offset mismatch" figure above. I am wondering how this circuit overcomes offset mismatch in this case.

50%
50%
jonharris0
jonharris0
7/12/2013 3:50:07 PM
User Rank
Blogger
Re: Calibration / DC components
Hi Dirceu, yes, a calibration procedure would definitely help.  When doing the calibration you'd need to make sure not to remove the DC content as many applications use content around DC.  As I mentioned, one approach would be to just make the offset of each ADC equal so you don't affect the incoming DC content of the input signal.

50%
50%
DirceuRodriguesJr
DirceuRodriguesJr
7/12/2013 12:58:45 PM
User Rank
Artist
Calibration / DC components
Jonathan,

  With ADC offset mismatches, a calibration procedures could help? Perhaps some kind of DC restore circuit (op. amp. or software based). I think in measuring devices, for example in the medical field: Unlike the ECG, an oximeter need the DC components of the signal.

100%
0%
More Blogs from Jonathan Harris
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.
Keeping the power supply inputs on separate domains can minimize crosstalk and make it much harder for noise to interfere with ADC performance.
flash poll
educational resources
 
follow Planet Analog on Twitter
Planet Analog Twitter Feed
like us on facebook
our partners
Planet Analog
About Us     Contact Us     Help     Register     Twitter     Facebook     RSS