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Altera_Forum
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15 years ago

FIR filter coefficient scaling and downscaling

I have a sensor signal which is unsigned 12 bits and i need to filter the signal using a FIR filter. The filtered output feeds into an algorithm which expects 12bit unsigned input. I have used...
Altera_Forum's avatar
Altera_Forum
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15 years ago

The FIR compiler scales the coefficients in a way, that the largest coefficient gets the maximum value in the choosen numeric format. To achieve a DC gain of 1 (respectively a power of 2), you have to use manual scaling. The rightmost "fixed point" column in the coefficient table shows the final coefficients used by the filter. Their sum should be a power of 2.