Split-Gate High-Side MOSFET Layout for Ringing and Overshoot
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Solution Overview
Problem
High-side MOSFETs in buck converters experience significant voltage overshoot and ringing effects due to increased switching speeds, leading to electromagnetic interference and reduced power efficiency.
Innovation Solution
A high-side switch device with split gates, comprising tie-gate and tie-source high-side switch devices connected in parallel, allowing the ratio of these devices to be adjusted to modulate Miller capacitance and control ringing and overshoot, ensuring operation within the FET's absolute maximum voltage rating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching speed is increased to reduce power loss, then power efficiency is improved, but voltage overshoot and ringing effects increase causing electromagnetic interference
Solution Approach 1:
The high-side switch device is segmented into multiple parallel-connected MOSFETs (first plurality and second plurality) with different gate structures. This segmentation allows independent optimization of each group's characteristics to balance switching speed and voltage control, resolving the contradiction between fast switching and reduced overshoot.
Solution Approach 2:
Different regions of the switch device have different gate structures: one region has MOSFETs with first gate structures optimized for fast switching, while another region has MOSFETs with second gate structures optimized for voltage control. This local quality differentiation allows simultaneous achievement of fast switching speed and reduced voltage overshoot in different parts of the system.
2Productivity
If switching frequency is increased to improve power efficiency, then conversion efficiency is improved, but ringing magnitude increases affecting system stability
Solution Approach 1:
The switch device is divided into multiple parallel MOSFET groups that can operate at different switching characteristics. This segmentation enables the system to maintain high conversion efficiency through increased frequency while the distributed structure reduces ringing magnitude and improves stability.
Solution Approach 2:
The patent uses a composite structure combining MOSFETs with different gate configurations in parallel. This composite approach creates a hybrid switching characteristic that achieves high efficiency while maintaining stability by leveraging the complementary strengths of different device types.
Data Source
AI summary
The present invention provides a high-side switch device having split gates. The high-side switch device includes: at least one tie-gate high-side switch device, each having a split gate independently connected to a gate; and at least one tie-source high-side switch device, each having a split gate independently connected to a source. The at least one tie-gate high-side switch device and the at least one tie-source high-side switch device are electrically connected in parallel. The quantity ratio of the at least one tie-gate high-side switch device to the at least one tie-source high-side switch device can be adjusted to modulate the Miller capacitance of the high-side switch device having split gates.