IIR filter implementation in verilog

Hi.

You have to truncate several least significant bits after addtion or to round the result, rounding is better (less level of self noise at the same data width). Actually data and coefficients resolution in IIR filters isn't a simple issue, because it influences filter characteristics and it's stability, self-noise, limit cycle probability and it's maximum level (under certain conditions IIR could generate a periodic signal at it's output even if input signal is zero).

Have a nice day.