FPGA implementation of high-order FIR filters by requantizing the input data stream
Chris Dick, Fred J. Harris · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1995
This paper addresses the problem of implementing narrow-band FIR filters using FPGAa. Rather than employing a conventional multiply-accumulate unit to compute the inner-product, an alternative method based on requantization of the input data stream is presented. The requantization process preserves the dynamic range of the signal components contained in the bandwidth of the filter, while shifting the requantization noise to the spectral region to be rejected by the filter. The reduced bit length representation of the requantization input data samples removes the requirement for a full multiplier in the filter hardware. This makes the method very attractive for realization using FPGA technology. The filtering technique is described, and implementation results using a Xilinx XC4010 FPGA are presented.