Active feedback pulsed measurement method
AssigneeThe Aerospace Corporation
InventorsAlbert M. Young, Samuel S. Osofsky
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Abstract
A pulse measurement method is applied to test devices such as high power FET transistors for measuring DC device parameters as well as for measuring S parameters during AC testing. The method uses an input gate bias tee for applying an accurately shaped pulsed input, a sensing bias tee for sensing terminal voltages, such as drain voltages for an FET, and a drive bias tee for coupling in a feedback signal provided by an active feedback circuit receiving AC coupled input error signal of the DC terminal voltage and for providing a drive signal as an error signal so as to maintain the applied DC test voltages at stable levels for improved accuracy.
Claims20
A method of testing a device under test (DUT) having an input terminal and an output terminal, the method comprising the steps of,
- DC applying a DC voltage level through AC sensing isolation to the output terminal,
- pulsed applying a pulsed input signal through AC input isolation to the input terminal, the pulsed input signal serving to activate the DUT to conduct output current through the output terminal at an output voltage level,
- DC sensing the output voltage level through the AC sensing isolation to provide a DC sensing signal
- AC sensing the DC sensing signal through AC feedback coupling to provide an AC feedback signal, and
- feeding back the AC feedback signal as a feedback drive signal through AC correction coupling and through AC drive isolation to provide the output current with a feedback drive signal for correcting the output current to stabilized the output voltage at a DC voltage level during the pulsed input signal.
A method of testing a field effect transistor (FET) having a gate terminal and a drain terminal, the method comprising the steps of,
- DC applying a DC voltage level through a sense bias tee providing AC sensing isolation to the drain terminal,
- pulsed applying a pulsed input signal through an input bias tee providing AC input isolation to the gate terminal, the pulsed input signal serving to activate the FET to conduct drain current through the drain terminal at a drain voltage level,
- DC sensing the drain voltage level through the AC sensing isolation to provide a drain sensing signal
- AC sensing the drain sensing signal through AC feedback coupling to provide an AC feedback signal, and
- feeding back the AC feedback signal as a feedback drive signal through AC correction coupling and through a drive bias tee providing AC drive isolation to provide the drain current with a feedback drive signal for correcting the drain current to stabilized the drain voltage at a drain voltage level during the pulsed input signal.
Dependencies are inferred from the claim text.