| 摘要 |
PROBLEM TO BE SOLVED: To reduce the multiplication number of times to half by using symmetric property of filter coefficient in an FIR filter in which a RAM is used for a buffer for delaying input data one by one. SOLUTION: If input data is written in a RAM-DF 21 to half (n/2 number) of degree n of the FIR filter 1, it is moved by reading sequentially the input data from written in most previously and by writing the data in a RAM-DS 22. If n/2 input data is written also in the RAM-DS 22, input data is read sequentially from the RAM-DS 22 which data is written in the last, while reading sequentially input data from the RAM-DF 21 which input data is written in most previously. Thus, two input data simultaneously read from the RAM-DF 21 and the RAM-DS 22 are added by an adder 4, and multiplication of the filter coefficient read from a RAM-CE 31 to the additional value is performed by a multiplier 5. Such a processing is repeated n/2 times, and totaling of the multiplication value is performed in a totaling circuit 6. COPYRIGHT: (C)2007,JPO&INPIT
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