| 摘要 |
PURPOSE:To obtain a circuit with extremely simple constitution by incorporating a digital filter, and also to execute attenuation with an abundant number of steps. CONSTITUTION:With respect to a data which is delayed by a shift register 1, an impulse response coefficient which is written in a coefficient ROM 2 is multiplied successively. Successively, by an accumulator 4, the data which is multiplied is added and outputted. By repeating said operation by shifting an input data, filtering is executed to a digital signal. When executing an attenuation, SWs 7-10 are all switched to the opposite side. As a result, the data which is inputted to a digital filter is multiplied by an attenuation coefficient which has been stored in a register 5, by a multiplier 3, and thereafter, inputted to a shift register 1. By repeating such an operation, an output of the digital filter is attenuated. |
