Series Thyristor Gate Merging for Overvoltage Protection
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Solution Overview
Problem
Thyristors in electronic devices often have high trigger voltages and low holding voltages, leading to unintended conduction during electrical overstress, which can result in device destruction, and existing solutions like cascoded thyristors increase both trigger and holding voltages and silicon surface occupancy.
Innovation Solution
A sequence of at least two thyristors coupled in series with their gates of the same conductivity type connected to form a single gate, increasing the holding voltage without significantly increasing the trigger voltage, and all thyristors are arranged in the same semiconductor body to minimize silicon surface occupancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three cascoded thyristors are used to increase holding voltage, then holding voltage is improved, but trigger voltage and surface occupancy increase
Solution Approach 1:
Multiple thyristors are merged by connecting their gates of the same conductivity type together to form a single gate, allowing them to be controlled by a single trigger circuit while maintaining series connection for voltage blocking. This merging approach increases holding voltage without proportionally increasing trigger voltage or device complexity.
Solution Approach 2:
The common gate structure serves multiple thyristors simultaneously, making the gate structure universal for controlling all series-connected thyristors. This multi-functionality reduces the number of separate trigger circuits needed and optimizes the trigger voltage requirement.
2Reliability
If three cascoded thyristors are used to increase holding voltage, then holding voltage is improved, but surface occupancy increases
Solution Approach 1:
The gate structures of multiple thyristors are merged into a single common gate, significantly reducing the total gate area required. This merging allows series-connected thyristors to share common regions, thereby reducing overall surface occupancy on silicon while maintaining the desired holding voltage.
3Reliability
If thyristors are arranged in series to increase holding voltage, then holding voltage is improved, but trigger voltage increases
Solution Approach 1:
By merging the gates of series-connected thyristors into a single common gate, the trigger voltage requirement is optimized. The common gate structure allows all thyristors to be triggered simultaneously at a lower voltage level compared to independent gating, while the series connection maintains the high holding voltage capability.
Data Source
AI summary
An electronic device is formed by a sequence of at least two thyristors coupled in series in a same conduction direction. Each thyristor has a gate of a first conductivity type. The gates of the first conductivity type for the thyristors in the sequence are coupled together in order to form a single control gate.