Rectifying Element With MOS Transistor and Schottky Diode
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Solution Overview
Problem
Switched-mode power converters face efficiency losses due to voltage drops in bipolar diodes, particularly at low power levels, which affect the overall efficiency of the converter.
Innovation Solution
The use of a rectifying element comprising a MOS transistor series-connected with a Schottky diode, where the transistor is configured to conduct when the Schottky diode is conducting, reducing the on-state voltage drop and improving efficiency by leveraging the lower threshold voltage of Schottky diodes compared to bipolar diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If bipolar diodes are used in switched-mode power converters, then the converter can operate reliably, but efficiency is reduced due to voltage drops especially at low power levels
Solution Approach 1:
The patent combines a MOS transistor and a Schottky diode into a single integrated rectifying element. The MOS transistor's source is connected to the Schottky diode's cathode, creating a unified component that leverages the low on-resistance of the MOS transistor to reduce voltage drops while maintaining the Schottky diode's fast switching characteristics, thereby improving efficiency without proportionally increasing manufacturing complexity
Solution Approach 2:
The rectifying element uses a composite structure combining two different semiconductor components (MOS transistor and Schottky diode) with complementary characteristics. The MOS transistor provides low on-state resistance for reduced conduction losses, while the Schottky diode provides fast reverse recovery, creating a hybrid component that outperforms traditional bipolar diodes in switched-mode power converter applications
2Loss of energy
If the transistor conducts when the Schottky diode is conducting, then voltage drop is reduced and efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent combines a MOS transistor and a Schottky diode into a single integrated rectifying element. The MOS transistor's source is connected to the Schottky diode's cathode, creating a unified component that leverages the low on-resistance of the MOS transistor to reduce voltage drops while maintaining the Schottky diode's fast switching characteristics, thereby improving efficiency without proportionally increasing manufacturing complexity
Solution Approach 2:
The patent changes the key parameter of on-state resistance by replacing the bipolar diode's high resistance path with the MOS transistor's low resistance channel. When the MOS transistor is turned on, it provides a low-impedance path that significantly reduces the voltage drop across the rectifying element, directly addressing the efficiency problem at low power 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
This configuration enhances the efficiency of switched-mode power converters, especially at low power levels, by minimizing voltage drops and maintaining high efficiency comparable to high-power operations.
Implementation Method 1
a rectifying element comprising a MOS transistor series-connected with a Schottky diode
Implementation Method 2
the transistor is configured to conduct when the Schottky diode is conducting
Data Source
AI summary
A rectifying element includes a MOS transistor series-connected with a Schottky diode. A bias voltage is applied between the control terminal of the MOS transistor and the terminal of the Schottky diode opposite to the transistor. A pair of the rectifying elements are substituted for diodes of a rectifying bridge circuit. Alternatively, the control terminal bias is supplied from a cross-coupling against the Schottky diodes. In another implementation, the Schottky diodes are omitted and the bias voltage applied to control terminals of the MOS transistors is switched in response to cross-coupled divided source-drain voltages of the MOS transistors. The circuits form components of a power converter.