VOLTAGE-APPLICATION CURRENT MEASURING INSTRUMENT AND CURRENT BUFFER WITH SWITCH USED THEREFOR

摘要

A voltage-application current measuring instrument for measuring the current flowing through a terminal of a device (DUT) under test to which a voltage from a DC power supply unit (220) is applied through a range selecting unit (210). The range selecting unit (210) has current buffers (CB1 to CBn) with switches corresponding to the current measurement ranges and current measuring resistors (R1 to Rn) each connected in series with the output of the corresponding current buffer. The voltage across the selected current measuring resistor connected in series is measured by a voltage difference measuring unit (150) to determine the current flowing through the terminal of the device. Each current buffer (CBi) has an output stage (12) connectable/disconnectable according to a control signal.