Integrated Temperature Diode in Power FET for Accurate Junction Sensing
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Solution Overview
Problem
Power switching circuit efficiency decreases with increasing FET operating temperature due to inaccurate temperature readings from temperature diodes in driver integrated circuits, which are affected by temperature differences between the driver IC and FETs in different semiconductor dies, leading to inefficiencies in power circuits.
Innovation Solution
Integration of a diode-connected bipolar transistor within the same semiconductor die as the power FET to provide accurate temperature information, allowing for improved circuit operation and energy efficiency by modifying switching signals based on precise temperature sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature diode is placed in the driver integrated circuit to monitor FET temperature, then temperature monitoring is enabled, but temperature measurement precision deteriorates due to temperature differences between the driver IC and FETs on different semiconductor dies
Solution Approach 1:
The patent merges the temperature sensing function directly into the FET die by integrating a temperature diode on the same semiconductor substrate as the power FET. This co-location ensures that the temperature diode measures the actual FET junction temperature rather than the driver IC temperature, eliminating the measurement inaccuracy caused by thermal differences between separate components.
Solution Approach 2:
The patent introduces a temperature diode as an intermediary element that is physically coupled to the FET die (either directly on the same die or in thermal contact). This intermediary provides an accurate temperature reading of the FET by being in direct thermal contact with it, while the driver IC remains separate and does not interfere with the temperature measurement accuracy.
2Reliability
If separate temperature sensors are used in driver dies, then temperature monitoring is implemented, but device complexity increases due to additional components and inter-die communication requirements
Solution Approach 1:
The patent combines multiple functions (power switching and temperature sensing) into a single FET die integration. The temperature diode is fabricated on the same semiconductor substrate as the power FET, eliminating the need for separate temperature sensor dies and reducing packaging complexity. This integration simplifies the overall device structure while maintaining accurate temperature monitoring capability.
Solution Approach 2:
The FET die is designed to serve multiple functions: it acts as both the power switching device and the temperature sensing platform. The temperature diode integrated on the same die provides temperature monitoring functionality without requiring additional dedicated sensor components, thereby reducing device complexity while achieving multi-functionality.
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
This approach enables accurate temperature monitoring and enhances energy efficiency in power switching circuits by providing precise temperature data directly from the FET, mitigating inaccuracies associated with separate temperature sensors in driver dies.
Implementation Method 1
a temperature diode with a cathode connected to the reference node, and an anode connected to a bias node
Data Source
AI summary
A device includes an epitaxial layer located over a semiconductor substrate, the epitaxial layer and the substrate both having a first conductivity type. A field-effect transistor (FET) includes source and drain regions having an opposite second conductivity type disposed in the epitaxial layer, and a gate structure over the substrate and between the source and drain regions. A diode includes first and second p-type regions and an n-type region all disposed in the epitaxial layer, the n-type region touching the first p-type region. A conductive plug electrically connects the first p-type region to the source region via the substrate.