Gate Driver Voltage Boosting for Lower MOSFET On-Resistance
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Solution Overview
Problem
Existing power supply circuits for switched-mode power supplies face challenges in achieving high current-driving capability while minimizing die area and switching loss, especially at low battery voltages.
Innovation Solution
The proposed solution involves a gate driver architecture that includes additional voltage domains to achieve higher gate-to-source voltage magnitude, reducing the drain-to-source on-resistance of switching transistors and decreasing conduction loss. This is achieved through a circuit design with specific switching devices and a voltage clamp, allowing for efficient gate driving with reduced transistor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the transistor size is increased to reduce on-resistance and conduction loss, then the current-driving capability and efficiency are improved, but the die area occupied by the power supply circuit increases
Solution Approach 1:
The patent changes the voltage parameter by introducing a third voltage rail with a voltage level different from the first and second voltage rails. This enables the gate driver to output a gate voltage with a larger magnitude relative to the source voltage, thereby reducing the on-resistance of the switching transistor without requiring a larger transistor size, thus resolving the contradiction between reducing conduction loss and minimizing die area
2Productivity
If additional voltage domains and switching devices are added to enhance current-driving capability, then the gate driving efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent designs the gate driver circuit where switching devices serve multiple functions: they act as both switching elements for controlling the power transistor and as part of the voltage generation network. The first and second switching devices control the output voltage level, while also being integral to the gate voltage generation mechanism, thereby enhancing current-driving capability without proportionally increasing circuit complexity
Data Source
AI summary
Techniques and apparatus for driving transistor gates of a switched-mode power supply (SMPS) circuit. One example power supply circuit generally includes a switching converter having a switching transistor and a gate driver having an output coupled to a gate of the switching transistor. The gate driver includes a first switching device coupled between the output of the gate driver and a first voltage rail; a second switching device coupled between the output of the gate driver and a voltage node of the gate driver; a third switching device coupled between the voltage node of the gate driver and a second voltage rail; and a voltage clamp coupled in series with a fourth switching device, the voltage clamp and the fourth switching device being coupled between a third voltage rail and the voltage node (or the output of the gate driver).