| 摘要 |
PURPOSE:To execute a measurement exactly at a high speed, by holding a value of a drain-source electric power source at necessary constant voltage, and controlling it by a switch as necessary. CONSTITUTION:A constant forward current [IF] is made to flow between the gate and the source by a constant-current power source 4 in a state that a switch 23 is opened, and at that time, gate-source voltage [VGS1] is set to the first sample holding circuit 12 in accordance with an enable signal (control signal at the time of input) from a controlling circuit, and is applied to an inverted input terminal of the first differential amplifier 17 through a resistance 14. In this case, a microcomputer, etc. are effective as the controlling circuit 21. Subsequently, the switch 23 is switched to the closed state, and the drain-source voltage is applied to the drain through a drain current detecting resistance 22 from a drain-source electric power source 3. |
