On-line Monitoring of the MOSFET Device Junction Temperature by Computation of the Threshold Voltage

A method for an on-line junction temperature measurement is introduced. The circuit allows the calibration of a real-time thermal model of a power MOSFET. A regular calibration of the real-time model provides an accurate thermal flux model over the lifetime of the power MOSFET. The measurement of threshold voltage is used to determine the device temperature. The paper presents the on-line measurement method, the circuit and test results.