Single-Chip MOSFET Synchronous Rectifier for Low-Loss Diode Emulation
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Solution Overview
Problem
Existing diode structures suffer from significant energy loss due to high forward voltage drop, which leads to power dissipation as heat, and require complex and costly configurations to reduce this loss, while also experiencing reverse current leakage.
Innovation Solution
A fully integrated single-chip MOSFET based synchronous rectifier is developed, utilizing two MOSFETs where the second MOSFET controls the first to enable unidirectional current flow, eliminating the need for external components and achieving a lower forward voltage drop by integrating all necessary components into a compact device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a traditional diode is used, then unidirectional current flow is achieved, but significant energy loss occurs due to high forward voltage drop
Solution Approach 1:
The patent changes the operating parameters by using a MOSFET instead of a traditional diode, utilizing the MOSFET's low on-resistance characteristic to achieve lower forward voltage drop and reduced power loss while maintaining unidirectional current flow functionality
Solution Approach 2:
The patent creates a diode-like functionality by using a MOSFET in a synchronous rectification configuration, where the MOSFET emulates diode behavior with improved electrical characteristics through controlled operation
2Loss of energy
If a Schottky barrier diode is used to reduce forward voltage drop, then power loss is reduced, but reverse current leakage increases significantly
Solution Approach 1:
The patent employs dynamic control of the MOSFET through synchronous rectification, where the MOSFET is actively switched on and off based on the current direction, enabling low forward voltage drop during conduction while blocking reverse current through the body diode, thus achieving both low power loss and low reverse leakage
Solution Approach 2:
The synchronous rectification circuit uses feedback control to detect current direction and timing, adjusting the MOSFET gate voltage accordingly to ensure optimal switching timing that minimizes both forward voltage drop and reverse current leakage
3Loss of energy
If a MOSFET synchronous rectifier is used to achieve low forward voltage drop, then power loss is reduced, but the circuit becomes bulky and complex with many discrete components
Solution Approach 1:
The patent integrates multiple functions into a single MOSFET device, combining the rectification function, control function, and protection function into one component, thereby reducing the number of discrete components and simplifying the overall circuit configuration while maintaining low power loss characteristics
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 achieves a significantly lower forward voltage drop, reducing power loss by up to 5.5 times compared to traditional Schottky diodes, with a Vf of less than 0.1V for over 90% of the on-state period, and exhibits lower reverse leakage, preventing thermal runaway at high temperatures, while simplifying fabrication and reducing manufacturing costs.
Implementation Method 1
a first field-effect transistor (M1) and a second field-effect transistor (M2), wherein the second field-effect transistor (M2) is adapted to control operation of the first field-effect transistor (M1) to thereby allow unidirectional current flow
Data Source
AI summary
A field-effect transistor (FET) based synchronous rectifier for emulating a diode, comprising: a first terminal (20) and a second terminal (30); a first FET (M1) and a second FET (M2), wherein the second FET (M2) is adapted to control operation of the first FET (M1) to thereby allow unidirectional current flow when the two terminals (20, 30) are connected with an external circuit; and wherein the FET based synchronous rectifier comprises a fully integrated single-chip device (10) adapted to emulate a diode.