[sdiy] Digital 4 pole filter in an FPGA

[Jim Patchell]

Now that is a really cool idea.  Not sure at this point exactly how many 
BRams I have left.  But that would be a very good use for one of them....

-Jim

ASSI wrote:
> On Tuesday 09 December 2008, Jim Patchell wrote:
>> Hope y'all aren't getting tired of these progress reports.
> 
> Not at all, just keep going. :-)
> 
> [...]
>> Now, also to give you an idea of exactly what I am doing, this is
>> basically the same kind of filter you would make with an
>> SSM2040...without, unfortunately, the non-linear distortion that is
>> inherent in the SSM2040.  I am not sure if I will be able to add a
>> non-linearity in the filter loop or not.  That may be some future
>> experiment.
> 
> If you haven't used up all BRAM resources you could pipeline through a 
> LUT set up in block RAM (you will likely need to do some 
> interpolation to keep the precision).  Using an LUT would have the 
> added benefit that you could try out tanh distortion just as well as 
> completely arbitrary waveshaping.
> 
> 
> Achim.

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