GaN Substrate Clamping Circuit for Bidirectional Switch dV/dt Control
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Solution Overview
Problem
Semiconductor-based circuits experience unpredictable performance due to voltage changes on the substrate, leading to undesirable voltage excursions, particularly during high-rate voltage transitions (dV/dt events), which affect the reliability and predictability of bidirectional switches.
Innovation Solution
A clamping circuit is implemented on a GaN substrate with a mirrored diode circuit to clamp positive dV/dt events and a mirrored switch circuit to clamp negative dV/dt events, using transistors and diodes to maintain substrate voltage within a threshold voltage range, thereby stabilizing the voltage during transient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If bidirectional switches operate during high-rate voltage transitions, then switching speed and power handling capability are improved, but voltage excursions on the substrate occur causing unpredictable circuit performance
Solution Approach 1:
A clamping circuit is introduced as an intermediary between the bidirectional switch and the substrate. This clamping circuit includes diodes and transistors that actively monitor and control substrate voltage, preventing harmful voltage excursions while allowing the bidirectional switch to operate at high speeds. The intermediary clamping circuit absorbs the harmful effects of rapid voltage transitions without restricting the switching performance.
2Device complexity
If substrate voltage is left uncontrolled during dV/dt events, then device complexity is reduced, but voltage excursions cause harmful effects on circuit operation
Solution Approach 1:
The clamping circuit is designed to automatically activate during dV/dt events without requiring external control signals. The diodes and transistors in the clamping circuit self-regulate based on the substrate voltage conditions, turning on only when voltage excursions occur and naturally clamping the voltage to safe levels. This self-service mechanism provides protection without adding complex control logic or increasing overall device complexity.
Data Source
AI summary
An electronic device includes a semiconductor substrate and a bidirectional transistor switch formed on the substrate, the bidirectional switch including a first source node, a second source node and a common drain node. A first transistor is formed on the substrate and includes a first source terminal, a first drain terminal and a first gate terminal, wherein the first source terminal is connected to the substrate, the first drain terminal is connected to the first source node and the first gate terminal is connected to the second source node. A second transistor is formed on the substrate and includes a second source terminal, a second drain terminal and a second gate terminal, wherein the second source terminal is connected to the substrate, the second drain terminal is connected to the second source node and the second gate terminal is connected to the first source node.