| 摘要 |
PROBLEM TO BE SOLVED: To realize a ramp-up ramp-down circuit capable of easily realizing smooth ramp-up and ramp-down without making a circuit scale large. SOLUTION: This circuit is provided with an n-stage shift register 102 successively shifting input data to a subsequent stage and AND gates 103-i (i=1 to n) in accordance with each stage of the register 102, and the transmission of an output of a corresponding stage is subjected to on-off control by a control signal 107-i from a control circuit 101. A multiplier 104-i multiplies data undergoing the on-off control by a prescribed filter coefficient, and a FIR filter output including ramp updown is derived by performing addition from the multiplication output in an addition circuit 105. A ramp updown signal is inputted to a shift register in the circuit 101, and ramp-up data is derived from an output of the circuit 105. The configuration is simple and the circuit scale is not large because a memory in which a filter coefficient at a time when ramp updown is performed is stored is not needed. |
