| 摘要 |
A parametric test system that will provide a forcing current at a predetermined level in one mode or a forcing voltage of a constant potential in another mode, particularly adapted for testing semiconductor devices. The circuit comprises a first amplifier means or voltage compliance amplifier which is an amplifier that produces the voltage compliance necessary for high voltage drive and measurement. The output of this compliance amplifier is controlled by a second amplifier means or control amplifier, both amplifiers being connected between current sources operating at negative and positive voltage levels, and this output is connected to one of two test terminals adapted for connection to the junction of a device under test. The control amplifier is "floating" in that it is referenced to one test terminal so that in the current forcing mode it produces an output that keeps driving the compliance amplifier to a different voltage level which in turn increases current flow at the test terminals. When current through the test junction reaches the predetermined level, set by means of an adjustable resistor, the control amplifier provides the proper output and the system stabilizes, with the first amplifier means maintaining the compliance voltage required. For voltage forcing, an external power source supplies voltage via the control amplifier to one test terminal. As leakage current tries to flow through the junction of the device under test, the potential at the test terminals change and cause an imbalance at the inputs to the control amplifier which changes its output and keeps driving the compliance amplifier to a different voltage level, until it is sufficient to cause leakage current to flow through the device under test. A measuring resistor is provided in the output of the compliance amplifier to facilitate access to test values.
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