Power MOSFET Intrinsic Diode as a Highly Linear Junction Temperature Sensor

The characteristics of a thermo-sensitive electrical parameter used to estimate the junction temperature of power MOSFETs are presented. In particular, the dependence on temperature of the voltage appearing across the forward-biased body-diode at fixed currents is carefully investigated experimentally in order to optimize linearity and sensitivity. Error, resolution and repeatability are also discussed. The intrinsic diodes have been characterized in a wide working temperature range, namely between 25 °C and 175 °C, and for 1000 fixed probe currents between 10 $\mu \text{A}$ and 10 mA. The results show that the temperature sensor has high sensitivity and high linearity. It is shown that the best trade-off between sensitivity and linearity can be obtained in a particular bias current range. Finally, the sensor long-term stability has been tested.