Design of narrow‐band FIR filters using interpolation technique

It is an important realization of digital filters to reduce the amount of hardware, notably multipliers. This paper proposes a cascade connection of IFIR (Interpolated FIR) filters by which a steep characteristic can be obtained with a small number of multipliers in most cases. the reduction of the multipliers is achieved by the determination of the transfer function of the overall cascade connection (not each element) by using the Lnorm approximation. This method also has an advantage in that its central frequency can be determined arbitrarily. the cascade connection of several elements reduces the degrading of its characteristic caused by the quantized coefficients as shown in examples, since the conditions required for each element are relaxed in this structure.