Series Switch Circuit Using a Third Transistor Against Shoot-Through
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Solution Overview
Problem
Shoot-through or short circuit conditions in electrical circuits, particularly in space applications, occur when both upper and lower switches turn on simultaneously due to high energy particles or noise, leading to overheating and switch failure.
Innovation Solution
A circuit design incorporating a third transistor connected in series with the first and second transistors, controlled by a gate driver circuit, which prevents shoot-through by pulling the first drive signal down to the source level of the second transistor when it is on, using gallium nitride field effect transistors for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If both upper and lower switches are turned on simultaneously during radiation events, then the circuit can handle high energy particle impacts, but shoot-through conditions occur causing overheating and switch failure
Solution Approach 1:
A third transistor is introduced as an intermediary component between the first and second transistors. This third transistor monitors the state of the second transistor and actively controls the gate drive signal to the first transistor, preventing simultaneous conduction. The intermediary transistor acts as a protective mediator that detects potential shoot-through conditions and intervenes to prevent them.
Solution Approach 2:
The gate driver circuit incorporates feedback mechanisms that monitor the state of the second transistor and adjust the drive signal to the first transistor accordingly. When the second transistor is detected to be in the on state, the feedback signal automatically pulls down the gate drive signal to the first transistor, ensuring it remains off and preventing shoot-through conditions.
2Reliability
If a third transistor is added to prevent shoot-through conditions, then reliability is improved, but device complexity increases
Solution Approach 1:
The gate driver circuit for the first transistor is merged with the control logic for the third transistor. The same gate driver that controls the first transistor also receives feedback from the second transistor state and uses the third transistor as an active protection element. This merging reduces the need for separate protection circuits and integrates the protection function into the existing control architecture.
Solution Approach 2:
The third transistor serves multiple functions: it acts as a protection element to prevent shoot-through, functions as a state monitor for the second transistor, and provides active control feedback to the gate driver. This multi-functionality reduces the need for additional dedicated protection components, thereby limiting the increase in overall circuit complexity.
Data Source
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AI summary
A circuit (400) comprising: first and second transistors (208, 210) connected in series; a third transistor, TT, (402) comprising a source (404) connected to a source (222) of the second transistor, ST, (210), a gate (406) connected to a gate (224) of ST (210), and a drain (226) connected to a gate (218) of the first transistor, FT, (208); and a gate driver circuit (270, 272) connected to the gates (218, 224, 406) of FT, ST and TT (208, 210, 402) and configured to provide (i) a first drive signal to the gate (218) of FT (208) to cause FT (208) to transition between an on state and an off state and (ii) a second drive signal to the gates of ST (210) and TT (402) to cause ST (210) and TT (402) to transition between on states and off states. The TT (402) is configured to prevent a shoot-through condition in the circuit (400) by pulling the first drive signal down to a level of the source (222) of the ST (210) when the ST (210) is in the on state.