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 μA 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.