MCM-based implementation of block FIR filters for high-speed and low-power applications

Block finite impulse response (FIR) digital filters have potential for high-speed and low-power realization through parallel processing. In this paper, we suggest an efficient implementation of block FIR filters using multiple constant multiplication (MCM) technique. Constant multiplication methods are widely used for reducing computational complexity of implementation of FIR filters. Sub-expression sharing for single constant multiplications can be performed for direct-form as well as transposed direct-form structures of FIR filters, while MCM techniques are not applicable to the direct-form FIR structure. On the other hand block FIR filters cannot be implemented in transposed direct-form. In this paper, we have shown that MCM can be used for direct-form implementation block FIR filters. Experimentation on block filters for filter orders 8 and 16 of different block lengths indicates that, compared to sample-by-sample MCM based transposed direct-form filters, the maximum sampling rate and energy delay product may be improved by up to 3.5 and 7.6 times respectively due to aggressive parallelization of block processing. It is also found that by using MCMs, up to 20% total area may be reduced compared to straightforward block filter implementation.