ANALYSIS OF EFFICIENT ARCHITECTURES FOR FIR FILTERS USING COMMON SUBEXPRESSION ELIMINATION ALGORITHM

Finite Impulse Response FIR filters are widely applied in multistandard wireless communications. The two key requirements of FIR filters are reconfigurability and low complexity. In this paper two reconfigurable FIR filter architectures are proposed namely Constant Shift Method CSM and Programmable Shift Method PSM. The complexity of linear phase FIR filters is dominated by the number of adders subtractors in the coefficient multiplier. The Common Subexpression Elimination CSE algorithm reduces number of adders in the multipliers and dynamically reconfigurable filters can be efficiently implemented. A new greedy CSE algorithm based on Canonic Signed Digit CSD representation of coefficients multipliers for implementing low complexity higher order FIR filters. Design examples shows that the filter architectures offer power reduction and good area and speed improvement over the existing FIR filter implementation.