Micro ammeter and micro current measurement method

摘要

PURPOSE:To judge the contact between a capacitive high resistance DUT, dc voltage generating source, and a fine ammeter, free from the change of connection, without installing a special circuit on a dc voltage generating source side. CONSTITUTION:When the resistance value of a DUT 3 is measured, an ac signal generating source 6 is separated from a measurement circuit, and the resistance value of the DUT is obtained from the measurement value of a fine ammeter and the value of a dc voltage source. When the contact between the DUT 3 and a connection terminal is judged, the ac signal generating source 6 is put into the measurement circuit. When the DUT 4 normally contacts the connection terminal, the circuit electric current is measured by a voltmeter 83 through a transformer 7, I/V converter 81, and a wave height detector 82, and the electrostatic capacity of the DUT 3 is measured form the electric current value and the voltage value of the ac signal generating source 6. If the DUT 3 does not contact the connection terminal, no electric current flows in the transformer, and a DUT connecting judging circuit 5 judges the noncontact state between the DUT 3 and the connection terminal with high precision.