Current attenuator useful in a very low leakage current measuring device.

摘要

An attenuator useful in measuring low level leakage currents is disclosed. The attenuator includes a plurality of current dividers coupled in cascade. Each current divider includes an input and two outputs between which the current entering the input is divided. The current exiting the last divider is significantly attenuated from that entering the attenuator. The attenuator output is coupled to the device under test and to one input of a differential amplifier. A known current is input to the differential amplifier and part is directed to the attenuator input and the other part to a current measuring device. The difference between the known current input to the differential amplifier and that measured is the current input to the attenuator. In the steady state, the current input to the differential amplifier from the current attenuator is about zero. Accordingly, the leakage current is equal to the known current entering the differential amplifier less the measured current divided by m, the attenuation provided by the attenuator.