| 摘要 |
PROBLEM TO BE SOLVED: To envelop smoothly an analog signal by comparing a signal voltage outputted from a signal generation part with an input analog signal voltage and attenuating the input analog signal voltage based on the comparison result. SOLUTION: In the signal generation part 1, a first capacitor 12 is charged while a switch 11 is closed by an ETCS signal, and the first capacitor 12 is discharged while the switch 11 is opened through a first resistor 13. Then, a connection point voltage between the first capacitor 12 and the first resistor 13 is attenuated smoothly to become an envelope signal. A comparison circuit part 2 compares an envelope signal voltage supplied to a base of a first transistor 21 with the analog signal voltage supplied to the base of a second transistor 22 through an operational amplifier 4 to output its difference as an emitter voltage of a third transistor 23. An attenuation circuit part 3 attenuates the analog signal inputted from an input terminal IN in response to an output from the comparison circuit part 2. |
