Power Switch Miller Protection Circuit for Fast Transistor Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fast-switching power transistors are prone to self-switching due to the Miller effect, leading to temporary short-circuits, and existing solutions either increase switching losses or are complex to implement.
Innovation Solution
A switch with a Miller effect protection unit, comprising a smaller protection transistor monolithically integrated with the power transistor, using a high-pass filter linking circuit and a control circuit to manage leakage current and voltage, preventing gate voltage rises and reducing switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage sensor and electrical source are used to limit switching current, then gate voltage rises are eliminated, but switching losses increase
Solution Approach 1:
The patent extracts and removes the problematic capacitance (Cgd) from the Miller effect pathway by using a protection transistor configured to bypass the gate-drain capacitance, allowing the main transistor to switch without the harmful feedback effect while maintaining low switching losses
Solution Approach 2:
The protection transistor acts as an intermediary element between the gate and drain, providing an alternative current path that prevents the Miller effect from causing gate voltage rises, thereby protecting the transistor without requiring complex voltage sensing and current limiting circuits
2Reliability
If transistor manufacturing methods are used to adjust capacitance values, then natural immunity to Miller effect is improved, but implementation complexity increases
Solution Approach 1:
The patent segments the transistor structure into a main power transistor and a separate protection transistor, where the protection transistor specifically addresses the Miller effect. This segmentation allows the protection function to be added without fundamentally changing the manufacturing process of the main transistor, reducing implementation complexity
Solution Approach 2:
The protection transistor serves multiple functions: it protects against the Miller effect, provides a discharge path for gate charge, and can be integrated into existing transistor fabrication processes. This multi-functionality achieves improved Miller effect immunity without requiring complex specialized manufacturing
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 solution effectively mitigates the Miller effect, enhancing the reliability and switching speed of power transistors while being easy to implement and reducing switching losses.
Implementation Method 1
the linking circuit, linking circuit being a high-pass filter for the leakage current of the transistor to be protected
Data Source
AI summary
A switch including a transistor to be protected, and a Miller effect protection unit including a protection transistor, the drain of the protection transistor being connected to the gate of the transistor to be protected, the source of the protection transistor being connected to the source of the transistor to be protected, a linking circuit, the linking circuit being a high-pass filter arranged between the gate of the protection transistor and the drain of the transistor to be protected, and a control circuit interposed between the gate of the protection transistor and the source of the transistor to be protected.