| 摘要 |
<p>PURPOSE:To perform a prompt measurement in wide dynamic range by selecting one output for low sensitivity when a detection for high sensitivity is saturated and selecting another output for high sensitivity when it is unsaturated, to make to a current measuring value. CONSTITUTION:A negative current (i) inputted to an input terminal I attains to the inverse input terminal IT1 of an operational amplifier IC1 with high input impedance but is not made to flow in the IC1 from the terminal IT1 during the current (i) is small since an input impedance of IC1 is high, and the current (i) comes to the output terminal OH of IC1 passing through a feedback resistor R2. So, a current-voltage conversion circuit CONV is formed with the amplifier IC1 and the resistor R2 during the current (i) is small and a sensitivity of that measurement is decided by the resistor R2. When an absolute value of the current (i) is increased and the output of amplifier IC1 is saturated, the current (i) begins to be shunted to a diode D1. However, the current unaffected by the circuit CONV is still made to flow to the resistor R1.</p> |
