Voltage-Resistant Switch Using Segmented FETs and Resistive Divider
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Solution Overview
Problem
Modern MOS components are vulnerable to damage from excessively high supply voltages due to the miniaturization of structures and smaller oxide thicknesses, which can lead to destruction, especially in circuits requiring voltage switching beyond the technologically maximally admissible gate-source voltage.
Innovation Solution
A voltage-resistant switch is designed using a combination of FET transistors with extended drains and gate connectors, along with resistors and control signal connectors, to manage and protect against high voltages by switching on and off the signal transmission, ensuring the components can withstand voltages up to 12V without damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oxide thickness of gate connectors is increased to improve voltage-resistance, then the voltage-resistance improves, but the electric properties of MOS transistors are impaired
Solution Approach 1:
The patent divides the switch into two separate FET transistors (first FET and second FET) with各自的 gate connectors. This segmentation allows each transistor to be optimized for specific voltage ranges, with the first FET handling higher voltages and the second FET handling lower voltages, thus resolving the contradiction between voltage-resistance and electric properties
Solution Approach 2:
The patent introduces a first resistor connected between the first gate connector and the second gate connector as an intermediary element. This resistor mediates the voltage distribution between the two FETs, ensuring that the gate-source voltage of each FET remains within safe limits while maintaining overall voltage-resistance capability
2Ease of operation
If the gate potential is increased to switch through voltage signals, then the switching capability improves, but the gate-source voltage exceeds the maximally admissible value causing damage
Solution Approach 1:
The patent uses two FET transistors with separate gate connectors to segment the voltage handling responsibilities. The first FET's gate connector is protected from excessive voltage by the resistor network, while the second FET handles the actual switching operation at safe voltage levels
Solution Approach 2:
The first resistor acts as an intermediary that limits and distributes voltage between the gate connectors, preventing the gate-source voltage from exceeding maximally admissible values while still enabling effective switching capability through coordinated operation of both FETs
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 protects MOS transistors from high voltages by dampening the input signal, preventing damage and ensuring safe operation within the voltage limits, while allowing signal transmission within safe voltage ranges.
Implementation Method 1
a second resistor, which is connected between the first channel and the second channel
Data Source
AI summary
A voltage-resistant switch is described. The switch comprises a signal input, a first FET transistor with a first channel with an extended drain and a first gate connector and a second FET transistor with a first channel with an extended drain and a second gate connector. A control signal connector is connected with the first gate connector and with the second gate connector via a second node and with the first channel and the second channel via a second resistor, and a signal connector is connected with the second channel. The voltage-resistant switch can be switched on and off.