Monolithic GaN Half-Bridge Level Shifting for Shoot-Through Prevention

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Solution Overview

Problem

Current half bridge power conversion circuits using GaN devices face challenges in efficiently converting high DC voltage to lower DC voltage while minimizing size and maximizing efficiency, particularly in high-frequency operations, due to issues with shoot-through prevention and voltage level shifting.

Innovation Solution

A half bridge circuit design incorporating GaN devices with integrated level shift and inverter circuits, including a low side and high side switch configuration, level shifters, pulse generators, and shoot-through protection circuits, to prevent simultaneous conduction of high and low side switches and manage voltage levels effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If GaN devices are used in half bridge power conversion circuits, then efficiency and frequency of operation are improved, but shoot-through prevention and voltage level shifting become more difficult

Engineering Contradiction:

Improvefrequency of operationVSAvoidvoltage level shifting complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent integrates the level shifter and inverter circuits directly onto the GaN device substrate, merging multiple functions into a single integrated structure. This eliminates the need for separate external level shifting components and simplifies the overall circuit architecture while maintaining high-frequency operation capabilities.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces an intermediary circuit structure that couples the low-side and high-side GaN devices through a controlled interface. This intermediary level shifter manages voltage transitions and prevents shoot-through conditions by providing controlled voltage level translation between the different potential domains.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If integrated level shift and inverter circuits are used, then circuit size is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvecircuit sizeVSAvoidintegration precision

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent segments the integrated circuit into distinct functional regions on the GaN substrate, with separate areas for the low-side circuit, level shifter, inverter, and high-side circuit. This segmentation allows for optimized layout and interconnection design, reducing the overall circuit footprint while managing manufacturing complexity through modular integration.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11888332B2Half-bridge circuit using monolithic flip-chip GaN power devices

Publication Date: 2024.01.30 NAVITAS SEMICON LTD

AI summary

GaN-based half bridge power conversion circuits employ control, support and logic functions that are monolithically integrated on the same devices as the power transistors. In some embodiments a low side GaN device communicates through one or more level shift circuits with a high side GaN device. Various embodiments of level shift circuits and their inventive aspects are disclosed.