| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reduce elements for switching a time constant as little as possible, to reduce a package cost, mounting area, and assembly cost in making an integrated circuit compared with a conventional circuit. <P>SOLUTION: When a switching contact 7a of a switch 7 is connected to a switching terminal 7b, a differential input 101 is activated, and an output terminal of an operational amplifier 5 in the last stage and a connecting point of a first resistor 11 are imaginarily shorted. The time constant of a time constant circuit 104 is decided by magnitude of a first and second resistors 11, 12 and a capacitor 13. When a switching contact 7a of a switch 7 is connected to the other switching terminal 7c, an another differential input 102 is activated, and a mutual connection point between the first and second resistors 11, 12 are imaginarily shorted. The time constant of the time constant circuit 104 is decided based on the magnitude of the second resistor 12 and the capacitor 13, thereby the time constant is variable by the capacitor 13. <P>COPYRIGHT: (C)2004,JPO</p> |
