4H-SiC Power MOSFET Body Diode as a Highly-Linear Temperature Sensor for TJ Monitoring

The performances of a thermo-sensitive electrical parameter used to estimate the junction temperature of 4H-SiC power MOSFETs are presented. In particular, the dependence on temperature of the body-drain voltage appearing across a forward-biased body-diode is investigated experimentally. The sensitivity, linearity, resolution, error and output repeatability are accurately discussed. The integrated diodes have been characterized in the temperature range between R.T. and 150 °C, with a forward current between 1 μ ~A and 1 μ ~A. The results have shown that the temperature sensor has both a high sensitivity (2.31-2.59 mV / C) and a high linearity (up to 99.97 %). The best trade-off between sensitivity and linearity has been found at a low bias current of 24 μ ~A. Finally, the long-term sensor stability has been accurately tested in order to evaluate how consistently it maintains a stable output over time.