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Altera_Forum
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17 years ago

Low Pass IIR filter using cyclone II FPGA

Hi everyone, I hava a task to implement low pass iir filter on cyclone II FPGA. The parameters of filter are the following: fp=5kHz; pass band frequency fs=8kHz; stop band frequency Fs=44k...
Altera_Forum's avatar
Altera_Forum
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17 years ago

OK, you gave me idea. I'will perform multiplication with all positive coefficients, and after multiplication I'will perform substraction instead of addition.

a1*x(n-1)-b1*y(n-1) =(a1*x(n-1)) - (b1y(n-1)) !

So my coeff will be +20.023... And now... how to perform multiplication of 18bit sampled digitalized value of input signal x and coefficient which have 18bits (6bits for number and 12bits for fractional part - 6.12)?

Sorry if I ask too much and if I ask nonsenses !

Bojan