Dual-Transistor Gate Control for Lower Transient On-Loss
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Solution Overview
Problem
Conventional semiconductor devices face challenges in reducing energy loss during the transient On-period in power transistors with switching functions.
Innovation Solution
A semiconductor device configuration that includes a first transistor, a second transistor, and a controller, where the second emitter region is longer than the first emitter region, and the controller applies specific voltage control strategies to manage the On and Off states of the transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional gate control techniques are used in power transistors, then steady-state On-voltage can be reduced, but energy loss during transient On-period increases
Solution Approach 1:
The invention divides the transistor structure into two separate transistors with independent gate control, allowing distinct control strategies for each transistor. The first transistor handles steady-state operation while the second transistor manages transient switching, enabling independent optimization of each device's performance characteristics without interfering with the other.
Solution Approach 2:
The controller applies a preliminary voltage to the second gate before the transient On-period begins, preparing the second transistor for rapid switching. This preliminary action reduces the switching time and minimizes energy loss during the transient period by ensuring the transistor is pre-conditioned for optimal switching performance.
2Loss of energy
If the second emitter region length is increased, then energy loss during transient On-period is reduced, but device area increases
Solution Approach 1:
The invention applies different emitter region lengths to different transistors based on their specific functional requirements. The second transistor, which handles transient switching, has a longer emitter region optimized for rapid carrier injection and low switching loss, while the first transistor maintains a standard emitter length suitable for steady-state operation, avoiding unnecessary area increase across the entire device.
Solution Approach 2:
The longer emitter region in the second transistor provides excessive carrier injection capability that ensures complete and rapid turn-on during transient periods. This partial exaggeration of the emitter length in only the critical transient-handling transistor achieves sufficient switching performance without requiring all transistors to have the larger dimension.
Data Source
AI summary
An object is to provide a technique that can reduce energy loss during the transient On-period. A semiconductor device includes a first transistor, a second transistor, and a controller. The controller is configured to, before the first transistor enters a transient Off-state, apply a second Off-voltage lower than a first Off-voltage to the second gate, before the first transistor enters a transient On-state, turn On the second transistor, and after the first transistor is turned On, apply the first Off-voltage to the second gate to turn Off the second transistor.