| 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 and a decimal section. A tone waveshape data generation circuit generates tone waveshape sampled data in response to the integer section of the address signal. A filter coefficient supply circuit 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 of the address signal. In a relation n=m/d, for example, the filter coefficient supply circuit 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 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. 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.
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