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Altera_Forum's avatar
Altera_Forum
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15 years ago

Filter output value is lower than expected

Hi, I have a fir compiler with the following settings: Input Bit Width: 16 Coefficient Scaling: Auto with 16 Bits Filter Type: LP with 37 Coefficients Sample Rate: ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

since you are truncating 17 bits,in effect you are dividing the sum of internal products by 2^17. Thus if you scale your coeffs as:

coeff = coeff/sum(coeff) *2^17 then you should get unity dc gain. but what actually happens at 1MHz may be due to your response