FET Switch Circuit for High-Voltage Isolation With Low Leakage
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Solution Overview
Problem
High voltage systems require expensive switches and additional protection circuits to connect and disconnect impedance between high and low voltage potentials, which are costly and difficult to stack, and often fail to meet isolation requirements.
Innovation Solution
A switch circuit using a field-effect transistor (FET) with an adjustment unit to control voltage and current, allowing for cost-effective connection and disconnection between high and low voltage potentials, and enabling standardized current limits and reduced leakage current, thus replacing expensive integrated switches and protection circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive integrated switches (e.g., PhotoMOS relays) are used to connect and disconnect impedance between high voltage and low voltage potentials, then switching reliability and isolation safety are improved, but system cost increases significantly
Solution Approach 1:
The patent divides the switch circuit into multiple discrete FETs (first FET, second FET) with specific configurations rather than using a single integrated switch. This segmentation allows independent optimization of each component and reduces overall system cost while maintaining reliability through the coordinated operation of multiple simpler components
Solution Approach 2:
The switch circuit is designed to perform multiple functions: switching impedance connection/disconnection, providing isolation between high and low voltage potentials, and enabling high voltage measurements when disconnected. This multi-functionality is achieved through the specific FET configuration rather than requiring separate dedicated components for each function
2Reliability
If additional protection circuits are added to integrated switches to meet safety standards, then system safety and isolation monitoring are improved, but device complexity and cost increase
Solution Approach 1:
The switch circuit inherently provides isolation safety and monitoring capabilities through its FET configuration without requiring additional external protection circuits. The circuit self-regulates to meet safety standards, eliminating the need for separate protection components and reducing overall complexity
Solution Approach 2:
The patent combines the switching function and protection/isolation function into a single integrated FET-based circuit design. The first and second FETs work together to simultaneously provide switching capability and inherent protection against high voltage hazards, merging multiple functions into one unified circuit
3Reliability
If standardized switches are used in high voltage systems, then current limit compliance is improved, but leakage current increases and cost increases
Solution Approach 1:
The patent optimizes the electrical parameters of the FETs (gate-to-source voltage, channel resistance) to achieve standardized current limits while minimizing leakage current. By carefully selecting and configuring FET parameters rather than using off-the-shelf standardized switches, the circuit meets current limit requirements with reduced harmful leakage
4Reliability
If switches are stacked in series to meet isolation requirements, then isolation capability is improved, but stacking difficulty and clearance requirements increase
Solution Approach 1:
The patent uses multiple discrete FETs configured in a specific arrangement to provide isolation capability. This segmented approach allows easier stacking and integration compared to monolithic integrated switches, as each FET can be independently positioned and connected to meet clearance requirements
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 reduces overall costs of high voltage systems by using discrete electronic components, meets regulatory current limits, and allows for easier stacking of switches while maintaining safety and isolation standards.
Implementation Method 1
a first field-effect transistor, first FET, which comprises a gate-terminal, a drain-terminal electrically connected to the first connection terminal, and a source-terminal electrically connected to the second connection terminal
Implementation Method 2
an adjustment unit, electrically connected to the control terminal and to the gate-terminal, the adjustment unit being adapted to alter a voltage and/or a current provided to the control terminal and to provide the altered voltage and/or current at the gate-terminal
Data Source
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AI summary
The present invention refers to a switch circuit (100) for connecting and disconnecting an electrical component between a high voltage potential and a low voltage potential. The switch circuit (100) comprises a control terminal (90), a first connection terminal (80) for the connection to a high voltage potential and a second connection terminal (70) for the connection to a low voltage potential. Moreover, the switch circuit (100) comprises a first field-effect transistor (60), which comprises a gate-terminal (61), a drain-terminal (62) electrically connected to the first connection terminal (80), and a source-terminal (63) electrically connected to the second connection terminal (70). Furthermore, the switch circuit (100) comprises an adjustment unit (50), electrically connected to the control terminal (90) and the gate-terminal (61), the adjustment unit (50) being adapted to alter a voltage and/or a current provided to the control terminal (90) and to provide the altered voltage and/or current at the gate-terminal (61).