Bootstrap Field Plate Control Circuit for Low-Loss MOS Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices, such as MOS transistors, face challenges in reducing on-resistance and switching loss.
Innovation Solution
A control circuit with a boot strap circuit including a capacitor and transistors is used to control the field plate voltage independently of the gate electrode, allowing for reduced on-resistance and faster switching times by inducing a high-density n-type accumulation layer in the semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the gate electrode voltage is increased to reduce on-resistance, then the on-resistance decreases, but the gate drive loss increases
Solution Approach 1:
The invention separates the control of the field plate electrode from the gate electrode. The field plate voltage is controlled independently through a dedicated control circuit (including switches S1-S4 and capacitors C1-C2), while the gate electrode is controlled by the gate drive circuit. This segmentation allows independent optimization: the field plate can be biased to reduce on-resistance without requiring increased gate drive voltage, thus reducing gate drive loss.
Solution Approach 2:
The field plate electrode acts as an intermediary between the gate drive circuit and the semiconductor layer. By applying voltage to the field plate through the control circuit, an electric field is induced that attracts carriers to the channel region, reducing on-resistance. This intermediary mechanism allows resistance control without directly increasing gate electrode voltage, thereby avoiding increased gate drive loss.
2Loss of energy
If conventional gate control is used, then the structure is simple, but switching loss is high
Solution Approach 1:
The control circuit performs preliminary action by pre-charging capacitors C1 and C2 during the off-state through switches S1 and S3. When switching to on-state, these pre-charged capacitors quickly discharge to apply the necessary field plate voltage, enabling fast switching. This preliminary charging action reduces switching loss by preparing the voltage in advance rather than charging during the switching transition.
Solution Approach 2:
The control circuit operates in periodic cycles, alternating between charging phase (off-state: switches S1, S3 closed) and discharging phase (on-state: switches S2, S4 closed). This periodic operation allows the field plate voltage to be reapplied in synchronization with the switching cycle, maintaining low on-resistance during conduction and enabling rapid switching transitions, thus reducing switching loss.
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 effectively reduces on-resistance and shortens switching times by controlling the field plate voltage independently, thereby minimizing gate drive loss and switching loss.
Implementation Method 1
a capacitor including a first terminal connected to a cathode of the diode and a second terminal electrically connected to the second bias terminal
Data Source
AI summary
According to one embodiment, a control circuit includes a first bias terminal, a second bias terminal, an input-side terminal, a diode, a capacitor, a first transistor, a second transistor, and an output-side terminal. The first transistor includes a first control terminal configured to turn on and off electrical conduction between a third terminal and a fourth terminal. The second transistor includes a second control terminal configured to turn on and off electrical conduction between a fifth terminal and a sixth terminal. A control signal based on a signal input to the input-side terminal is input to the first control terminal and the second control terminal, and the first transistor and the second transistor are alternately turned on and alternately turned off.