Multiplexer Switch Segmentation for Voltage Handling
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Solution Overview
Problem
Conventional multiplexers for liquid crystal displays require high voltage switches to handle large voltage differences, leading to increased costs and potential damage, as they need to be fabricated using high voltage semiconductor processes.
Innovation Solution
A multiplexer design with a third input terminal and additional switch units that allow for a series connection of switches, enabling operation with a third voltage intermediate to the first and second voltages, reducing the voltage difference across each switch and allowing for lower endurance voltage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage switches are used to handle large voltage differences, then the multiplexer can transmit voltages with large differences, but the fabrication cost increases and the device complexity increases
Solution Approach 1:
The first switch unit is divided into two switches connected in series, creating two separate voltage paths. This segmentation allows each switch to handle a smaller voltage difference individually, enabling the use of lower voltage switches that are cheaper to fabricate while still handling the overall large voltage difference between V1 and V2.
Solution Approach 2:
A third input terminal providing an intermediate voltage V3 is introduced as a mediator. This intermediate voltage serves as a reference potential that reduces the voltage difference across each switch. By using V3 as a mediator, the switches only need to handle voltage differences relative to V3 rather than the full difference between V1 and V2, allowing lower voltage switches to be used.
2Adaptability or versatility
If high voltage switches are used to handle large voltage differences, then the multiplexer can operate with large voltage ranges, but the switch endurance voltage requirement increases
Solution Approach 1:
The first switch unit with two series-connected switches segments the voltage handling requirement. Each switch only needs to endure a portion of the total voltage difference, specifically the difference between V1/V2 and the intermediate voltage V3, rather than the full V1-V2 difference. This segmentation reduces the endurance voltage requirement for each individual switch.
Solution Approach 2:
The system changes the reference voltage parameter from directly comparing V1 and V2 to comparing both against an intermediate V3. This parameter change transforms the voltage difference that each switch must handle from (V1-V2) to approximately (V1-V3) and (V3-V2), where each difference is smaller than the original total difference, reducing endurance requirements.
3Reliability
If switches are required to have higher endure voltage, then damage prevention is improved, but the device complexity and fabrication process complexity increase
Solution Approach 1:
Dividing the first switch unit into two series-connected switches reduces the voltage stress on each component, improving reliability and damage prevention.同时，这种分割使得每个开关可以在较低电压下工作，从而可以使用标准的低电压半导体工艺进行 fabrication，避免了复杂的高电压工艺需求，降低了制造复杂性。
Solution Approach 2:
By changing the voltage reference parameter to use an intermediate voltage V3, the system reduces the voltage difference across each switch. This parameter change allows switches to operate at lower voltages, improving damage prevention while enabling the use of standard low-voltage fabrication processes instead of complex high-voltage processes.
Data Source
AI summary
A multiplexer includes: a first switch unit coupled between a first input terminal and an output terminal and including a series connection of first and second switches; a second switch unit coupled between a second input terminal and the output terminal; and a third switch unit coupled to a third input terminal and a common node between the first and second switches. Different first and second voltages, and a third voltage greater than one of the first and second voltages and less than the other one of the first and second voltage are applied respectively to the first, second and third input terminals. The multiplexer is operable between a first mode, where the first voltage is transmitted to the output terminal, and a second mode, where the second voltage is transmitted to the output terminal and the third voltage is transmitted to the common node between the first and second switches.