GaN 2DEG Temperature Sensing for HEMT Junction Monitoring
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Solution Overview
Problem
Challenges exist in accurately measuring the junction temperature of gallium nitride (GaN) high electron mobility transistors (HEMTs) in switching power converter circuits due to the absence of bipolar junction transistors or diodes in their manufacturing process, which are typically used for temperature sensing.
Innovation Solution
Incorporating a temperature sensor circuit with a two-dimensional electron gas (2DEG) resistive element directly on the GaN IC die and using a complementary metal oxide semiconductor (CMOS) IC die to measure the resistance of the 2DEG channel, which varies linearly with temperature, along with a stable zero-temperature coefficient voltage reference to generate a temperature sense current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If wide bandgap devices (GaN HEMTs) are used as switching devices, then power conversion efficiency and voltage handling capability are improved, but temperature measurement capability deteriorates due to absence of bipolar junction transistors or diodes in manufacturing process
Solution Approach 1:
The patent introduces a two-dimensional electron gas (2DEG) channel as an intermediary element that serves the temperature sensing function traditionally performed by bipolar junction transistors or diodes. The 2DEG channel's resistance varies predictably with temperature, allowing it to act as a mediator between the GaN HEMT operating conditions and the temperature measurement requirement, thus resolving the contradiction between using wide bandgap devices and maintaining temperature measurement capability
Solution Approach 2:
The patent utilizes the temperature-dependent resistance parameter of the 2DEG channel to enable temperature sensing. By monitoring changes in the resistance parameter of the 2DEG channel with temperature variations, the system achieves temperature measurement capability without requiring traditional bipolar junction transistors or diodes, thereby maintaining both the efficiency benefits of GaN HEMTs and the temperature measurement function
2Volume of moving object
If GaN HEMTs are used for high voltage and power levels, then device size is reduced, but temperature monitoring accuracy deteriorates without integrated temperature sensing elements
Solution Approach 1:
The patent merges the temperature sensing function with the existing GaN IC die structure by utilizing the 2DEG channel that is already present in the GaN HEMT device. This integration approach combines the power switching function and temperature sensing function within the same GaN IC die, achieving accurate temperature monitoring without adding separate sensing components that would increase device size
Solution Approach 2:
The GaN HEMT device serves its own temperature monitoring needs through the 2DEG channel that is inherently part of its structure. The 2DEG channel's resistance naturally varies with temperature, allowing the device to self-monitor its thermal state without requiring external or separate temperature sensing elements, thus maintaining compact size while enabling accurate temperature monitoring
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately monitors the temperature of GaN HEMTs, enabling protective measures against overheating and improving the efficiency and reliability of GaN-based switching power converters.
Implementation Method 1
using a complementary metal oxide semiconductor (CMOS) IC die to measure the resistance of the 2DEG channel, which varies linearly with temperature
Data Source
AI summary
A temperature sensor circuit includes a gallium nitride (GaN) integrated circuit (IC) die including a temperature sensitive two-dimensional electron gas (2DEG) resistive circuit element that includes a 2DEG channel; and a sensing circuit included to sense resistance of the temperature sensitive 2DEG resistive circuit element.