To reduce the circuit scale of a filter by holding analog data corresponding to a filter characteristic, executing a product-sum operation with digital data on analog data making the number of bits on the filter characteristic to be larger than that of digital data.

Digital data ai on which a filter characteristic is reflected is converted into analog data A(t) by a D/A conversion circuit 11 and it is inputted to sample-and-hold circuits SH1-SHn in parallel. Analog data corresponding to the filter characteristic which is sample-held are multiplied by digital data X1-Xn as base band signals in multiplication circuits M1-Mn and the multiplication result is added in an addition circuit 12. The number of bits on digital data ai as a filter coefficient is made to be larger than that of digital data Xi for transmission. The number of capacitors and whole capacity in the multiplication circuits in a product-sum operation means are reduced and a circuit area is reduced.