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
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.