Integrated Switch Protection Circuit for Miller Effect Suppression
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Solution Overview
Problem
Existing power transistors experience self-switching phenomena due to the Miller effect, leading to temporary short circuits and increased switching losses, with existing solutions being complex or inefficient.
Innovation Solution
A switch design incorporating a protection unit monolithically integrated with the transistor, utilizing a smaller protection transistor and a capacitor to mitigate the Miller effect through a high-pass filter and control circuit, reducing parasitic elements and implementing a passive protection mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage sensor and electrical source are used to adjust the driving value and limit switching current, then the Miller effect is eliminated, but switching losses increase
Solution Approach 1:
The patent extracts the protection function from complex external circuits (voltage sensor and electrical source) and implements it through a simplified integrated protection unit with a protection transistor and capacitor directly connected to the transistor gate, thereby reducing switching losses while maintaining Miller effect protection
Solution Approach 2:
The protection unit operates autonomously using the transistor's own parasitic capacitance and a simple RC circuit, eliminating the need for external voltage sensing and active control, thus reducing switching losses without compromising protection effectiveness
2Reliability
If transistor manufacturing processes are adjusted to change capacitance values, then natural immunity to Miller effect is improved, but implementation complexity increases
Solution Approach 1:
Instead of modifying the transistor manufacturing process directly, the patent introduces an intermediary protection unit consisting of a protection transistor and capacitor that works alongside the existing transistor, simplifying implementation while achieving Miller effect immunity
Solution Approach 2:
The patent segments the protection function from the main transistor structure, implementing it as a separate but integrated protection unit with its own transistor and capacitor, thereby avoiding complex manufacturing process changes while improving natural immunity
3Reliability
If a protection transistor with larger dimension is used, then protection effectiveness is improved, but parasitic elements increase
Solution Approach 1:
The patent optimizes the protection transistor dimensions and capacitor value to achieve the right balance: the protection transistor is sized sufficiently to provide effective protection while keeping parasitic elements minimal, with the capacitor value specifically chosen to filter high-frequency switching noise without excessive size
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 reduces switching losses and enhances reliability by synchronously addressing the Miller effect, allowing faster switching and minimizing parasitic elements while being easy to implement.
Implementation Method 1
the connection circuit (20) is a capacitor (26) arranged between the gate (18G) of the protection transistor (18) and the drain (12D) of the transistor to be protected (12). The capacitor (26) blocks a direct or low-frequency current and allows a flow of high-frequency current
Implementation Method 2
utilizing a smaller protection transistor and a capacitor to mitigate the Miller effect through a high-pass filter and control circuit
Data Source
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AI summary
The present invention relates to a switch (10) comprising: - a transistor to be protected (12), and - a Miller effect protection unit (14) comprising: - a protection transistor (18), the drain (180) of the protection transistor (18) being connected to the gate (12G) of the transistor to be protected (12), the source (18S) of the protection transistor (18) being connected to the source (12S) of the transistor to be protected (12), - a linking circuit (20), the linking circuit (20) being a high-pass filter disposed between the gate (18G) of the protection transistor (18) and the drain (120) of the transistor to be protected (12), and - a control circuit (22) interposed between the gate (18G) of the protection transistor (18) and the source (12S) of the transistor to be protected (12).