Calculation of a scalar product in a direct-type fir filter

(57) Summary book invention relates to the method of calculating a scalar product within a direct type FIR filter and a FIR filter, and the method of designing a direct type FIR filter. The continuation word which is a digital input signal is delayed within the delay line which has delay (50A*50D) of 1-word duration, and the scalar product between the word which is guided from a delay line and which was delayed variously and a corresponding fixed coefficient is calculated. According to the present invention, calculation of a scalar product combines 1 bit of the two or more bits words in an input (X0) and the outputs (X0*X4) of a delay line at a time within the subtractor of the (a) bit serial, and/or an adding machine element network (51*56), However, it consists of what at least one bit serial element multiplies the multiplication operation of at least two different coefficients by the multiplication result from an element network by 関り and involution of 2 (49 A*K), and the result is totaled, and a scalar product (45*48) is produced for.