| 摘要 |
<p>PURPOSE:To measure the amount of a current from an extremely low level to a high level with one range by performing linear amplifying operation in a fine current area and logarithmic amplifying operation in an area above it. CONSTITUTION:When an input current I0 is small and the output voltage of an amplifier 3 is lower than the voltage of a power source 22, an amplifier 3 performs linear output operation. At this time, the output of an amplifier 33 is made ineffective through a contact b4. On the other hand, when the current I0 increases and the output voltage of the amplifier 3 rises above the voltage of the power source 22, a switching circuit 6 operates and then while the amplifier 3 enters the logarithmic output operation, the output of the amplifier 33 is supplied to the input of an amplifier 34. Further, the output of a power source 21 is made lower than that of the power source 22 to prevent hunting. The output value right before the amplifier 3 in linear output operation enters logarithmic output operation is made nearly equal to the output value after the amplifier enters the logarithmic output operation to standardize a measurement scale.</p> |
