Variable statistical wordlength in digital filters

Statistical wordlength calculations estimate the wordlength to which a digital filter's coefficients can be rounded and still be likely to meet the specification. The value of this wordlength has generally been dominated by the sensitivity of the magnitude response to a small subset of filter coefficients. If variable wordlengths are used, more bits can be assigned to sensitive coefficients and fewer to insensitive coefficients, allowing the average wordlength (and hence implementation complexity) to be reduced. The paper investigates the variable wordlength technique as applied to minimax IIR filter designs. Significant reductions in filter complexity over the uniform wordlength method result.