JPS6419817A - Digital filter - Google Patents

Abstract

PURPOSE:To obtain a digital filter having a prescribed direct current gain by matching a circuit network having a digital adder, multiplier and an unit delay element and a simple digital multiplier to the respective factors of a digital transfer function H(z). CONSTITUTION:The simple multiplier 1 corresponding to a coefficient C1-n and digital signal data is inputted for every prescribed sampling cycle. The circuit network (z) is constituted of the adder 21, a substracter 22, the multipliers 23, 24 and the unit delay element 25 and to the adder 21, the output of the multipliers 1, 23 is inputted, to the substracter 22, the output of the adder 21 and the multiplier 24 is inputted, to the multipliers 23, 24, the output of the unit delay circuit 25 is inputted and to this unit delay circuit 25, the output of the adder 21 is inputted. The multiplier 23 corresponds to a coefficient C2-n and the multiplier 24 corresponds to a coefficient C3-n. The direct current gain is constantly a prescribed value and a signal level is not fluctuated.