Current-Sensing Semiconductor ESD Circuit for Dual-Polarity Protection
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Solution Overview
Problem
Semiconductor devices used in power electronics face challenges in accurately sensing current through a load path without damaging the sense transistor due to electrostatic discharge (ESD).
Innovation Solution
Incorporating an ESD protection component with an ESD transistor and resistor, which provides double polarity protection by creating low inductance paths for dissipation of ESD, thereby increasing the robustness of the current-sensing component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sense transistor is used to sense current through the load path, then accurate current sensing is achieved, but the sense transistor is vulnerable to damage from electrostatic discharge due to its small size
Solution Approach 1:
The patent introduces an ESD protection component as an intermediary element between the sense transistor and the external environment. This component includes an ESD transistor with a discharge path that acts as a mediator to capture and divert electrostatic discharge away from the sense transistor, thereby protecting it while allowing the sense transistor to continue its accurate current sensing function
Solution Approach 2:
The patent segments the protection function from the sensing function by introducing a separate ESD protection component. The ESD transistor and its discharge path are separated from the sense transistor circuit, allowing each component to be optimized independently - the sense transistor for accurate measurement and the ESD transistor for robust discharge protection
2Reliability
If the ESD transistor gate is connected to the discharge path, then ESD of first polarity is dissipated through the transistor, but the discharge path must handle both polarities requiring additional components
Solution Approach 1:
The patent makes the discharge path universal by incorporating a diode that enables the same path to handle both first polarity and second polarity ESD events. The diode allows current flow in both directions, making the discharge path multi-functional and eliminating the need for separate protection circuits for each polarity, thus reducing overall device complexity
Solution Approach 2:
The patent converts the potentially harmful second polarity ESD into a beneficial protective mechanism by using the diode to guide the discharge current through the ESD transistor's intrinsic body diode. This transforms what would be a damaging reverse polarity event into a controlled dissipation path that protects the sense transistor
3Measurement precision
If separate testing of main and sense transistors is performed, then accurate individual characterization is achieved, but testing time increases and ESD damage risk during testing increases
Solution Approach 1:
The patent merges the testing of the main transistor and sense transistor into a single simultaneous testing operation. The ESD protection component enables both transistors to be tested together through the same test circuitry, reducing testing time and minimizing the risk of ESD damage during the testing process while still allowing accurate individual characterization of each transistor
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
The ESD protection component effectively dissipates ESD of both polarities, protecting the sense transistor and ensuring accurate current sensing without damage, while also allowing simultaneous testing of main and sense transistors, reducing testing time and risk of ESD damage.
Implementation Method 1
an electrostatic discharge (ESD) protection component configured to protect the current-sensing component from an electrostatic discharge
Data Source
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Figure 3A
AI summary
A semiconductor device comprising: a power switching component configured to control the flow of current through a load path; a current sensing component configured to sense the current flow through the load path; and an electrostatic discharge "ESD" protection component configured to protect the current-sensing component from an electrostatic discharge, wherein the ESD protection component comprises an ESD transistor, the ESD transistor having a gate which is connected to a discharge path such that the presence of a discharge of a first polarity causes the ESD transistor to switch on to form a further path for dissipation of a discharge.