PURPOSE: To make it possible to reduce greatly a quantization error of an upper split electrode, by quantizing upper and lower electrodes by rounding, omitting or raising to a unit according to a relation between the quantization error and minimum quantization step.

CONSTITUTION: Of a split electrode transversal filter using CCD, the minimum quantization step is denoted by L, and the quantization error of the upper split electrode by ΔW. Here, if 0≤ΔW<L/4 and 3L/4≤ΔW/L, both electrodes are rounded for quantization. However, both electrodes are omitted in case of L/4≤ ΔW<L/2 or raised to a unit if L/2≤ΔW<3L/4. Consequently, the quantization error can greatly be reduced.