Digital finite-impulse-response (FIR) filter with a modified architecture based on high order Radix-N numbering

摘要

A fast FIR filter 100, a system, and a method that increases the operating speed of a filter. The system uses a high order numbering system, in particular Radix-8, and appropriate control lines, parallel data buses 101 and simple circuits for coefficient pre-multiplying. In a typical application, incoming high-speed unequalized 6-bit data are encoded into the high order numbering system, and placed on two data buses 101, one containing the high order data bit stream, e.g., 4 bits for Radix-8, and the other the low order data bit stream, e.g., 3 bits for Radix-8. The data are further encoded in “hot-one” mode so that at all times exactly one bit is asserted. FIR coefficients are calculated, requiring pre-multiplication for only four non-trivial cases in the case of Radix-8 encoding: C, −C, 3C, and −3C, where C is a coefficient value. Because the coefficients do not change at high data rates, high-speed operation of pre-multiplication is not required. Further, by using the “hot-one” property incorporated in each bus, a simple low-propagational delay passgate multiplexer can be used for pre-multiplying.