PURPOSE: To reduce the level of a noise mixed from the digital filter part of the D/A conversion device with monolythic digital filter to an analog part.
CONSTITUTION: This device is provided with a converting means 2 for converting an inputted digital signal based on fixed rules, RAM 3 for storing the output of the converter, ROM 7 for storing a filter coefficient, inverse converting means for returning the data read from the RAM 3 to its original value, digital filter equipped with a multiplier 6 and an accumulator 10 for convolving the data successively read from the RAM 3 with the filter coefficient through the inverse converting means 4, and D/A converter 12 for converting the digital filter output to an analog value, the data written in the RAM 3 are made random and especially when a fine signal is inputted, the change of a current amount to flow to the RAM 3 is suppressed at a minimum.
SOBASHIMA AKIRA
TANI YASUNORI
HATANAKA HIDEAKI
