Dual-Transistor Gate Control for Active Clamp Back-EMF
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Solution Overview
Problem
Current semiconductor devices face challenges in efficiently managing counter electromotive forces during active clamp operations, leading to potential damage and rapid temperature rises due to the limitations in their gate control and drain-source voltage management.
Innovation Solution
The semiconductor device incorporates a dual-transistor structure with a control circuit that allows for independent control of first and second transistors, where the first transistor is switched off during active clamp operations, and the second transistor handles the counter electromotive force, utilizing a specific gate control circuit and active clamp circuit configuration to manage voltages and currents effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single transistor structure is used, then the device complexity is low, but the active clamp tolerance is insufficient and the device is vulnerable to damage from counter electromotive forces
Solution Approach 1:
The patent divides the single transistor into two separate transistors (first transistor and second transistor) with independent gate control. The first transistor handles normal operation while the second transistor is specifically designed to withstand counter electromotive forces during active clamp operations. This segmentation allows each transistor to be optimized for its specific function, improving overall reliability without requiring a completely new device architecture.
2Reliability
If the first transistor is kept on during active clamp operations, then the on-resistance remains low, but the transistor is damaged by counter electromotive forces causing rapid temperature rise
Solution Approach 1:
The patent implements dynamic control of the first transistor's gate signal. During active clamp operations when counter electromotive forces occur, the gate control circuit automatically turns off the first transistor to protect it from damage. The second transistor remains on to maintain low on-resistance and handle the current. This dynamic switching based on operational conditions resolves the contradiction between protection and performance.
3Reliability
If independent gate control circuits are added for each transistor, then the active clamp tolerance is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The gate control circuit is designed with multi-functionality to manage both transistors. It can selectively control the first transistor during normal operation and the second transistor during active clamp operations, or control both simultaneously when needed. This universal control approach reduces the need for completely separate control circuits, thereby reducing manufacturing complexity while maintaining the reliability benefits of independent transistor control.
Data Source
AI summary
A semiconductor device includes an insulated gate type first transistor that is formed at a semiconductor chip, an insulated gate type second transistor that is formed at the semiconductor chip, and a control wiring that transmits a control signal controlling the first transistor and the second transistor to reach an ON state during a normal operation and controlling the first transistor to reach an OFF state and the second transistor to reach an ON state during an active clamp operation.