GaN HEMT Gate Drive Voltage Generation Without Extra Power Rails
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Solution Overview
Problem
GaN HEMTs require a low, tightly controlled voltage to turn on completely, but standard electronics components often provide insufficient voltage, leading to susceptibility to noise and increased complexity and cost when separate power rails are used to drive them.
Innovation Solution
A drive voltage generator that uses a fixed input and a square wave input to generate output voltages greater than 3.3V and negative voltages without additional supply rails, by charging capacitors with a portion of the fixed voltage and adjusting gate-source voltages of transistors to achieve desired voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate power rails are used to drive the eGaN HEMT, then the gate-source voltage requirement is met, but the system complexity and cost increase significantly
Solution Approach 1:
The patent combines multiple power rail functions into a single supply voltage source. The voltage translation circuit generates both the elevated positive voltage (for full conduction) and negative voltage (for turn-off) from one power rail, eliminating the need for separate power rails while meeting all gate-source voltage requirements
Solution Approach 2:
The patent uses voltage translation to dynamically change voltage parameters. The circuit translates the single supply voltage into multiple voltage levels including positive voltages above the threshold (5V-6V) and negative voltages for turn-off, adapting voltage parameters as needed without additional power rails
2Device complexity
If a standard power line (0-3.3V supply) is used to drive the eGaN HEMT, then the system complexity is reduced, but the gate-source voltage is insufficient for full conduction
Solution Approach 1:
The patent changes the voltage parameter from the standard 0-3.3V supply to elevated voltage levels (5V-6V positive and negative voltages) through voltage translation. This parameter transformation enables full conduction of the eGaN HEMT while maintaining system simplicity by using a single power rail
3Reliability
If charge pump based approach is used for negative turn-off bias generation, then stable negative voltage is achieved, but additional components and circuit complexity are introduced
Solution Approach 1:
The patent merges the negative voltage generation function with the existing voltage translation circuit. The same circuit that generates positive voltage also produces negative voltage by translating the single supply voltage, combining multiple functions into one integrated solution rather than adding separate charge pump components
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient driving of GaN HEMTs with on-state voltages greater than 5V and negative off-state voltages without additional supply rails, reducing complexity and cost while maintaining stable operation.
Implementation Method 1
a first capacitor connected to the square wave input... When the square wave voltage is low, load, by the first circuit, the first capacitor with a portion of the fixed voltage... When the square wave voltage is high, the generator adds the high voltage to the portion of the fixed voltage of the first capacitor
Implementation Method 2
a second capacitor connected to the square wave input... When the square wave voltage is high, the second circuit loads the second capacitor with a portion of the high voltage... When the square wave voltage is low, the generator reduces the load of the second capacitor by the high voltage such that it becomes a negative voltage
Implementation Method 3
The first circuit keeps a gate-source voltage of the first transistor below a first threshold voltage of the first transistor... increase the gate-source voltage of the first transistor above the first threshold voltage, such that the high voltage and the portion of the fixed voltage of the first capacitor is provided through the transistor
Data Source
AI summary
According to an aspect of the present disclosure, a drive voltage generator for driving a GaN high electron mobility transistor is provided. According to another aspect there is provided a GaN high electron mobility transistor unit including a GaN high electron mobility transistor, and a drive voltage generator connected to the GaN high electron mobility transistor. A method for generating a drive voltage for a GaN high electron mobility transistor is also provided.