Method and apparatus for eliminating deadband in digital recursive filters

Abstract From the Canadian patent

Method and apparatus for eliminating deadband effects in digital recursive filters caused by rounding of the quantization of products within the filter wherein the product, is represented by a digital word consists of truncating the, absolute value of the product-representing word to the next lower digit by dropping a number of least significant digits determined by the value of the multiplier and if any of the dropped digits is a "one", adding a least significant one to the truncated number while retaining the sign of the pre-truncated word, and repeating the process at the cycling frequency of the filter until a steady state is reached at which the difference between the input and output …