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

ADC Power Supplies: Inputs

Jonathan Harris
jonharris0
jonharris0
6/9/2014 10:30:30 AM
User Rank
Blogger
Re: Starting supplies - requirements
Another good point.  I discussed a little about PSRR back in my December blog: http://www.planetanalog.com/author.asp?section_id=3041&doc_id=562140

I'll be continuing to look at power supply schemes in my upcoming blog and try to point out some topologies and strategies to help mitigate any issues from power supply noise.  Stay tuned! :-)

Thanks for both of these great questions/comments!

50%
50%
jonharris0
jonharris0
6/9/2014 10:26:24 AM
User Rank
Blogger
Re: avoiding crosstalk
That is a very good question.  Unfortunately, those are internal design details.  Care is taken inside the ADC to minimize crosstalk and part of this is to separate the supply domains at the pins of the device.  As you have pointed out there are also frequency relationships inside the ADC that must be evaluated...but those are part of the 'secret sauce' inside the device. :-)

50%
50%
etnapowers
etnapowers
6/3/2014 11:25:53 AM
User Rank
Master
avoiding crosstalk
"There are various portions of circuitry within each of these blocks that operate at different frequencies, and keeping the supply domains separate helps keep these frequencies from making their way back and forth between the two sections. Having crosstalk between these sections can result in degraded performance, which may manifest itself in the SNR (noise performance) or the SFDR (spurious performance) of the ADC."

 

I wonder if there is a guideline to establish the minimum value of difference between the frequencies that prevents crosstalk, which affects the performances of the ADC.

50%
50%
RedDerek
RedDerek
6/2/2014 11:18:43 AM
User Rank
Master
Starting supplies - requirements
Best place to start, besides voltage levels, is allowed ripple on the supply. This would then be the PSRR. And thus can affect how the supply is designed - frequency for one. Is is always best to use a high frequency power supply? Challenges here is that the dynamic range of output power is reduced at higher frequencies. (I ask these questions only to get the conversation started.)

50%
50%
More Blogs from Jonathan Harris
Lets discuss the preparation for IMS2016 and preview the show a bit.
In this installment Id like to revisit the example that was covered in my January blog post
We will continue looking at the AD9680 as an example just as we did in part 1. Similar to the real mode operation of the DDC the normalized decimation filter responses are the same regardless of speed grade.
Lets now take a closer look at the decimation filtering and how ADC aliasing influences the effective response of the decimation filtering
Increase the decimation ratio in the DDC to see the effects of frequency folding and translating when a higher decimation rate is employed along with frequency tuning with the NCO.
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