| 摘要 |
An address signal generation circuit generates an address signal which changes at a rate corresponding to tone pitch of a tone to be generated. This address signal consists of an integer section (IAD) and a decimal section (FAD). A tone waveshape data generation circuit (13) generates tone waveshape sampled data in response to the integer section (IAD) of the address signal. A filter coefficient supply circuit (24) can generate data corresponding to filter coefficients of m orders and selects and supplies n filter coefficients (where n < m) in response to the decimal section (FAD) of the address signal. In a relation n = m/d, for example, the filter coefficient supply circuit (24) selects filter coefficients corresponding to n orders which are distant sequentially with an interval of d in response to the value of the decimal section of current address signal. A digital filter operation circuit (21) performs filter operations of m orders with respect to tone waveshape data of n sample points by using these n filter coefficient data and tone waveshape data of n sample points generated by the tone waveshape data generation circuit (13). By this arrangement, despite that the actual filter operation is carried out only with respect to data corresponding to the n orders, a filter operation equivalent to performing filter operations of m orders can be realized. |
