| 摘要 |
PURPOSE:To reduce effectively unpleasant noise when an input output characteristic is changed without much increase in the circuit scale. CONSTITUTION:A random number generating circuit 1 gives a random pulse signal active at an irregular time interval to an interpolation circuit 2. The interpolation circuit 2 interpolates the coefficient K between a precedingly set value and a set value this time just after the coefficient K is changed and a trigger signal TRG is received to change stepwise from the precedingly set value till the set value this time and gives the result to a multiplier 3. A timing for stepwise change is given as an irregular time interval by a count-up enable signal CE. The multiplier 3 controls the amplitude of the input signal DIN based on the coefficient K' to output an output signal DOUT. Thus, no rapid amplitude change is caused in the output signal DOUT and the periodicity of it is eliminated, then the production of noise sensed in an audible sense is prevented. |
