Segmented Gate Drive Circuit for EMI and Turn-On Loss
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Solution Overview
Problem
Switch mode power supplies generate electromagnetic interference (EMI) due to fast switching of power devices, and existing methods to mitigate this, such as using gate drive resistors, result in high turn-on loss and packaging challenges.
Innovation Solution
A drive circuit with multiple drive units that control charging and discharging currents segment by segment, eliminating the need for gate drive resistors, thereby reducing EMI and packaging complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a gate drive resistor is used to reduce EMI by slowing down the turn-on speed, then EMI is reduced, but turn-on loss increases significantly
Solution Approach 1:
The gate drive charging process is divided into multiple segments with different current levels. The first drive unit provides a first charging current, the second drive unit provides a second charging current, and the third drive unit provides a third charging current. By segmenting the charging process, the patent reduces EMI during the Miller plateau while maintaining faster charging capability, thereby reducing turn-on loss.
Solution Approach 2:
The gate drive circuit dynamically adjusts the charging current based on the real-time voltage at the gate end. When the voltage reaches the first threshold, the circuit switches from the first drive unit to the second drive unit. When the voltage reaches the second threshold, it switches to the third drive unit. This dynamic adjustment optimizes both EMI reduction and turn-on speed.
2Object-affected harmful factors
If a gate drive resistor is used to control turn-on speed, then EMI is reduced, but packaging complexity increases
Solution Approach 1:
The patent merges the gate drive circuit and the power device into a single integrated package. The frame serves as both the structural support and the packaging substrate, eliminating the need for separate gate drive resistors and their associated packaging. This integration simplifies the packaging structure and reduces packaging complexity.
Solution Approach 2:
The patent extracts and eliminates the gate drive resistor from the traditional packaging structure. By removing this external component and its associated packaging requirements, the patent simplifies the overall packaging complexity while maintaining EMI reduction through the multi-unit drive circuit integration.
Data Source
AI summary
A drive circuit includes a first drive unit, a second drive unit, and a third drive unit. The first drive unit is configured to: when receiving a first control signal, output a first drive charging current to a gate end, so that a voltage at the gate end reaches a first threshold. The second drive unit is configured to output a second drive charging current to the gate end, so that the voltage at the gate end reaches a second threshold from the first threshold. The third drive unit is configured to: after the voltage at the gate end reaches the second threshold, output a third drive charging current to the gate end. The third drive charging current is greater than the first drive charging current and the second drive charging current. In this way, a turn-on loss may be reduced while meeting an electromagnetic interference requirement of the power device.