GaN Controller Stabilizes Gate Voltage via Current Sensing Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
GaN-based semiconductor devices face stability issues due to reduced driving voltage caused by voltage drop across sampling resistors, leading to unexpected switching off during high-frequency operations.
Innovation Solution
A controller is designed with a low dropout regulator and step-up converter to generate a stable driving voltage for GaN-based devices, using a current sensing signal to maintain a fixed gate-to-source voltage equal to the reference voltage, thereby stabilizing the switching operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sampling resistor is connected in series with the MOSFET for sensing drain current, then current sensing is achieved, but the driving voltage is significantly reduced due to voltage drop across the sampling resistor causing stability problems
Solution Approach 1:
The patent introduces an intermediary voltage compensation mechanism that measures the voltage drop across the sampling resistor and adds it back to the driving voltage. This mediator (compensation circuit) ensures that the gate-to-source voltage remains stable despite the voltage drop caused by current sensing, thereby maintaining both sensing accuracy and switching stability.
Solution Approach 2:
The patent implements a feedback mechanism where the voltage drop across the sampling resistor is continuously monitored and fed back to the controller. The controller then adjusts the driving voltage accordingly to compensate for the drop, ensuring that the gate-to-source voltage remains at the required level for stable GaN HEMT operation throughout the switching cycle.
2Ease of operation
If the driving voltage is reduced due to voltage drop across sampling resistor, then current sensing is enabled, but the gate-to-source voltage becomes unstable causing unexpected switching off
Solution Approach 1:
The patent introduces an intermediary voltage compensation mechanism that measures the voltage drop across the sampling resistor and adds it back to the driving voltage. This mediator (compensation circuit) ensures that the gate-to-source voltage remains stable despite the voltage drop caused by current sensing, thereby maintaining both sensing accuracy and switching stability.
Solution Approach 2:
The patent applies preliminary anti-action by pre-compensating for the expected voltage drop across the sampling resistor. The controller anticipates the voltage drop and proactively increases the driving voltage before the GaN HEMT switching event, preventing the gate-to-source voltage from dropping below the threshold and causing unexpected turn-off.
3Device complexity
If a conventional controller is used for Si MOSFET with sampling resistor, then simple control is achieved, but it causes stability problems when driving GaN-based HEMT
Solution Approach 1:
The patent implements a feedback mechanism where the voltage drop across the sampling resistor is continuously monitored and fed back to the controller. The controller then adjusts the driving voltage accordingly to compensate for the drop, ensuring that the gate-to-source voltage remains at the required level for stable GaN HEMT operation throughout the switching cycle.
Solution Approach 2:
The patent dynamically changes the driving voltage parameter based on the detected voltage drop across the sampling resistor. By adjusting the magnitude of the driving voltage in real-time according to the current sensing conditions, the controller maintains stable gate-to-source voltage for GaN HEMT operation while accommodating varying current levels.
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
The solution ensures stable operation of GaN-based semiconductor devices by maintaining a consistent gate-to-source voltage, eliminating the impact of voltage drops across current sensing resistors and ensuring full switching on and operation in the saturation region.
Implementation Method 1
a step-up converter connected to the CS node and configured to convert the reference voltage Vref to a step-up voltage VDD which is given by VDD=Vref+VCS
Data Source
AI summary
The present disclosure provides a controller for controlling a GaN-based semiconductor device. The controller is configured to receive a current sensing signal VCS which is indicative of a drain-to-source current of the GaN-based semiconductor device and generate a control driving signal VDRV to the GaN-based semiconductor device such that a gate-to-source voltage VGS applied to the GaN-based semiconductor device for switching on the GaN-based semiconductor device is stabilized to a voltage value equal to a reference voltage Vref over an on-time duration. Impact of the change in the voltage drop across the current sensing resistor to the operation of the GaN-based semiconductor device is eliminated.