Monolithically Integrated Temperature Sensor Based on p-GaN/AlGaN/GaN Heterostructure

A monolithically integrated temperature sensor circuit based on a p-GaN/AlGaN/GaN heterojunction is proposed. The sensor comprises two parts: the first part is a temperature-sensitive voltage source formed by a two-dimensional electron gas (2DEG) resistor and a schottky barrier diode (SBD) in series, and the second part is a resistor-transistor logic (RTL) inverter formed by a 2DEG resistor and a p-GaN high electron mobility transistor (HEMT) in series. The output voltage of the temperature-sensitive voltage source is connected to the gate of the p-GaN HEMT in the second part, providing the gate voltage. According to data obtained from TCAD simulation results, the output voltage of the temperature-sensitive voltage source exhibits positive temperature dependence. The output voltage of the RTL inverter exhibits a negative temperature dependence. When the temperature sensor is properly biased, the voltage division between the SBD and the 2DEG resistor in the temperature-sensitive voltage source reallocates as the temperature rises, causing the gate voltage of the connected RTL inverter to increase. This increasement enhances the temperature-induced variation in the RTL inverter's output voltage, increasing the sensitivity of the temperature sensing circuit from 4 mV/K with a fixed gate voltage to 14 mV/K. This simulation demonstrates a compact monolithic integration sensor for monitoring the on-chip temperature of GaN power integrated circuits for protection and control.