MOSFET Type Transistor-Thermistor for Thermal Sensors
Details
Principle on the transistor-thermistor of the bipolar transistor developed by us is extended to that of the MOSFET. Characteristics of the MOSFET in the subthreshold region are similar to that of the bipolar transistor, namely, the source of MOSFET corresponds to the emitter of bipolar transistor, the pre-channel to the base, and the drain to the collector in the subthreshold of the MOSFET. It was confirmed using a commercial p-channel MOSFET and a fabricated p-channel MOSFET that the drain current Id in this subthreshold region had an exponential factor for the ambient temperature T under a constant gate-voltage Vg and a constant drain-voltage Vds. This fact means that the drain-resistance Rd in the subthreshold region of the MOSFET can be treated as a thermistor under the constant Vds, and its thermistor-constant B can be varied with Vg, as seen in the transistor thermistor of the bipolar transistor.
