We propose a novel in-situ approach for monitoring the variations in the on-resistance of power transistors in switching-mode operation. The device under test (DUT) is operated in a synchronous buck converter; a feedback loop, acting on the duty cycle of the DUT, is used to keep the output voltage constant, even in presence of variations of device properties. An increase in the equivalent resistance of the DUT is sensed by monitoring the variation of the duty cycle during operation, through an oscilloscope-based setup. The test is "in-situ" since device operation does not need to be interrupted for sensing the variations in on-resistance. The effectiveness of the proposed approach is verified by evaluating the increase in on-resistance induced by the self-heating of a silicon MOSFET. This approach can be useful to evaluate changes in the on-resistance of FETs induced by long-term reliability tests, or by a variation in device heating induced by a variation in the thermal resistance of the devices. In addition, the same approach can be used also for evaluating the impact of charge-trapping phe-nomena in novel technologies, based on novel semiconductors as SiC and GaN.
A novel in-situ approach to monitor the variations in the on-resistance of power transistors during switching operation
Cavaliere, A.;De Santi, C.;Meneghesso, G.;Zanoni, E.;Meneghini, M.
2023
Abstract
We propose a novel in-situ approach for monitoring the variations in the on-resistance of power transistors in switching-mode operation. The device under test (DUT) is operated in a synchronous buck converter; a feedback loop, acting on the duty cycle of the DUT, is used to keep the output voltage constant, even in presence of variations of device properties. An increase in the equivalent resistance of the DUT is sensed by monitoring the variation of the duty cycle during operation, through an oscilloscope-based setup. The test is "in-situ" since device operation does not need to be interrupted for sensing the variations in on-resistance. The effectiveness of the proposed approach is verified by evaluating the increase in on-resistance induced by the self-heating of a silicon MOSFET. This approach can be useful to evaluate changes in the on-resistance of FETs induced by long-term reliability tests, or by a variation in device heating induced by a variation in the thermal resistance of the devices. In addition, the same approach can be used also for evaluating the impact of charge-trapping phe-nomena in novel technologies, based on novel semiconductors as SiC and GaN.
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