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Altera_Forum
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8 years ago

Estimation IIR filter resources

Hi, In my application I will need implement high order (4), IIR, Butterworth, Low Pass filter, with cutoff frequency (-3dB) of ~1Hz and stop band of ~10Hz, with attenuation of -80dB. The input si...
Altera_Forum's avatar
Altera_Forum
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8 years ago

Sounds like you haven't built your design yet. Here's some statistics for you: A 1998 tap FIR filter, applied to 24-bit input samples, using 24-bit taps, will (roughly) require four multiplies, 12 altsyncram's, 206 dff's, and 2148 lcell's and some I/O buffers. This is based upon a quick Yosys run.

A quick check of my favorite FIR generation script suggests that a 21 tap FIR, quantized to 24 bits, will meet your criteria with a (rough) 130dB stop band. Overdesigned? Perhaps.

What's missing in this discussion are such components as you might need to get your ADC input, to drive a DAC on the back end, and any components you might need to debug your design.

Somehow I don't think the filter you just described will be the limiting factor in your design.

Dan