To realize desired frequency characteristic and desired phase characteristic at the end of a screen without increasing a circuit scale.
A digital filter includes a data forming means 102 for forming N pieces of input data, multiplying means 107-113 each for multiplying N pieces of factors supplied from a factor forming means 103; factor switching means 104, 105 each for supplying by changing the factors of a first group corresponding to invalid input data, and the factors of a second group symmetrical to the factors of the first group to 0 to the multiplying means 107-113 when at least one of the N pieces of the input data formed with the data forming means 102 is invalid; and factors summing means 106 for adding the factors of the first group corresponding to the invalid input data and the factors of the second group symmetrical to the factors of the first group to the factor of a center tap and supplying to the multiplying means 107-113.
Hironori Honda
Toshimitsu Ichikawa
Takeshi Takamatsu
Yuriko Hamada