SiC MOSFET Dual-Mode Sense Terminal for Current and Temperature
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
SiC-based power MOSFETs have a smaller chip area and high current density, leading to weaker short-circuit ability and reduced short-circuit withstand time, necessitating improved current and temperature sensing methods to prevent faults like short circuits and overcurrent situations, which existing external detection methods are slow to detect and cannot address effectively, especially for half-bridge configurations.
Innovation Solution
Integration of a dual mode sense terminal and a doped resistor region in the SiC substrate between a power transistor and a current sense transistor, allowing for alternating between current and temperature sensing using the same sense terminal, with a toggle device to switch between sensing modes, enabling quasi-simultaneous monitoring of both parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external detection methods (Hall sensors, desaturation detection) are used for current and temperature sensing, then device complexity is reduced, but detection speed is slow and fault detection capability is insufficient
Solution Approach 1:
The patent merges current sensing and temperature sensing functions into a single integrated on-chip sensor system. The sense transistor is integrated within the power device structure, allowing simultaneous monitoring of both current (via drain current) and temperature (via intrinsic carrier concentration effects) at the same location, thereby improving detection speed and reliability while eliminating the need for separate external sensors
Solution Approach 2:
The patent uses the sense transistor as an intermediary element that indirectly measures both current and temperature parameters. The sense transistor's drain current serves as a mediator that reflects both the main power device current and temperature conditions, enabling fast detection without requiring direct measurement of each parameter separately
2Measurement precision
If separate sense cells are created using additional lithography process steps, then current and temperature sensing precision is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The sense transistor structure is designed to perform multiple functions: it senses current through its drain current, senses temperature through intrinsic semiconductor effects, and can also serve as part of the power device structure itself. This multi-functionality eliminates the need for separate dedicated sense cells and additional lithography steps, reducing manufacturing complexity while maintaining sensing precision
Solution Approach 2:
The sense transistor utilizes the power device's own operational parameters (drain current, threshold voltage shifts) to self-diagnose both current and temperature conditions. The sensing mechanism leverages the inherent electrical characteristics of the semiconductor structure itself, requiring no external components or additional fabrication processes
3Adaptability or versatility
If five terminals are used for power device operation and sensing, then sensing functionality is complete, but chip active area is reduced and package utilization is low
Solution Approach 1:
The patent combines current sensing and temperature sensing into a single sense transistor with shared terminals. The drain terminal of the sense transistor is shared with the main power device, and a single sense terminal is used for both current and temperature measurements by alternating measurement modes, thereby reducing the number of required terminals from five to four and increasing chip active area
Solution Approach 2:
The patent employs periodic switching between current sensing mode and temperature sensing mode using the same sense terminal. A switching circuit alternates the connection of the sense terminal between current measurement configuration and temperature measurement configuration, enabling dual-function sensing with a single terminal through time-division multiplexing
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 enhances power electronics self-protection by providing timely detection of faults, reducing wafer fabrication complexity and cost, and allowing for effective prevention of device failures in safety-critical applications like battery electric vehicles.
Implementation Method 1
a doped resistor region in the SiC substrate between the power transistor and the current sense transistor, wherein the dual mode sense terminal is electrically connected to source and body regions of the current sense transistor, wherein the doped resistor region has a same conductivity type as the body regions of both of the transistors and is configured as a temperature sense resistor that electrically connects the source terminal to the dual mode sense terminal
Implementation Method 2
a power transistor and a current sense transistor integrated in the SiC substrate such that the current sense transistor is configured to mirror current flow in the main power transistor
Data Source
AI summary
A semiconductor die includes: a SiC substrate; power and current sense transistors integrated in the substrate such that the current sense transistor mirrors current flow in the main power transistor; a gate terminal electrically connected to gate electrodes of both transistors; a drain terminal electrically connected to a drain region in the substrate and which is common to both transistors; a source terminal electrically connected to source and body regions of the power transistor; a dual mode sense terminal; and a doped resistor region in the substrate between the transistors. The dual mode sense terminal is electrically connected to source and body regions of the current sense transistor. The doped resistor region has a same conductivity type as the body regions of both transistors and is configured as a temperature sense resistor that electrically connects the source terminal to the dual mode sense terminal.