AD6636: multiple channel Filter design

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Feb 23, 2016
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As AD6636_multiple channel Filter design.docx shown, it describe how to combine
the filtering resources of multiple channels. And here two channels' example is
given.
1. For the RCF filter of one channel, I think we can use Softcell to design it,
isn't it?
2. If there are 6 channels, which value should be programmed into Decimation
Phase Bits of 6 channels?

 

You can use softcell to design your filter using multiple channels.  Set
softcell up for your design just as you normally would and then just reduce
your output rate by a factor of two each time you double the number of
channels.  I have attached a filter file showing the recommended method to use
multiple channels to implement a filter.   In this example the filter would
have a 122.88MHz input rate and a 7.68MHz effective output rate.  However,
since I’m planning to use 4 channels the output rate that I use in softcell is
1.92Mhz.  This allows softcell to use more taps to generate the filter.  I then
need to decimate by the amount of channels I plan to use in the CRCF (or DRCF)
filter – so in this case I decimate by 4 in the CRCF.

Once you get you filter in the part we normally split the channels at the
intermediate data router.  We then decimate by a multiple of the number of
desired channels in the DRCF or CRCF (in this case by 4in the CRCF) and use the
decimation phase to delay the channels.  Take a look at the filter and let me
know if  you have additional questions.

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