Design of Extrapolated Impulse Response FIR Filters With Residual Compensation in Subexpression Space

In this paper, an extrapolated impulse response filter with residual compensation is proposed for the design of discrete coefficient finite-impulse response (FIR) filters using subexpression sharing. The proposed technique utilizes the quasi-periodic nature of the filter impulse response to approximate the filter coefficients. The reduced degree of freedom of filter coefficients due to the quasi-periodic approximation is perfectly restored by introducing a residual compensation technique. The resulting subexpression sharing synthesis of discrete coefficient FIR filters has lower complexities than that of the conventional synthesis techniques in terms of number of adders. To further reduce the synthesis complexity, filter coefficients and residuals may be optimized in subexpression spaces. Mixed integer linear programming is formulated for the optimization. Numerical examples show that the number of adders required by synthesizing the filters in the proposed structure is significantly reduced compared to that of the conventional synthesis schemes synthesized in direct or transposed direct form.