Test apparatus and test method

1. A test apparatus for testing a device under test, the test apparatus comprising:

a reference voltage supply section for supplying a reference voltage;

a field effect transistor provided between a positive side terminal and a negative side terminal of the reference voltage supply section so that a drain terminal and a source terminal of the field effect transistor are in parallel connection with the device under test;

an inductance that is connected between the positive side terminal and the negative side terminal of the reference voltage supply section, the inductance being in serial connection with the device under test between a positive-side power supply terminal and a negative-side power supply terminal of the device under test, and being in serial connection with the field effect transistor between the drain terminal and the source terminal of the field effect transistor;

a control section for controlling a gate voltage of the field effect transistor, thereby changing a power supply voltage to be supplied to the device under test; and

a judgment section for judging quality of the device under test, based on characteristic of the device under test in accordance with change in the power supply voltage.

2. The test apparatus as set forth in claim 1 , wherein

the judgment section judges the quality of the device under test, based on a power supply current value consumed by the device under test when the power supply voltage is changed.

3. The test apparatus as set forth in claim 1 , wherein

the control section, by decreasing the gate voltage, increases the power supply voltage with a gradient designated in advance.

4. The test apparatus as set forth in claim 1 , wherein

the control section conducts a first test in which the power supply voltage is raised from a first power supply voltage to a second power supply voltage while keeping the first reference voltage supplied from the reference voltage supply section, and

on condition that no defect for the device under test is found in the first test, the control section conducts a second test in which the power supply voltage is raised from a voltage value substantially the same as a voltage value of the first power supply voltage to a third power supply voltage that is higher than the second power supply voltage, while keeping the second reference voltage supplied from the reference voltage supply section, the second reference voltage being higher than the first reference voltage.

5. A test method for testing a device under test by means of a test apparatus, the test apparatus including:

a reference voltage supply section for supplying a reference voltage;

a field effect transistor provided between a positive side terminal and a negative side terminal of the reference voltage supply section, so that a drain terminal and a source terminal of the field effect transistor are in parallel connection with the device under test; and

an inductance that is connected between the positive side terminal and the negative side terminal of the reference voltage supply section, the inductance being in serial connection with the device under test between a positive-side power supply terminal and a negative-side power supply terminal of the device under test, and being in serial connection with the field effect transistor between the drain terminal and the source terminal of the field effect transistor,

the test method comprising:

a control step for controlling a gate voltage of the field effect transistor, thereby changing a power supply voltage to be supplied to the device under test; and

a judgment step for judging quality of the device under test, based on characteristic of the device under test in accordance with change in the power supply voltage.