Level Shift Circuit Using an Intermediate Voltage Domain
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Solution Overview
Problem
Current display device level shift circuits face challenges as transistors break down when high voltage or voltage differences exceed their withstand threshold, leading to increased complexity and cost in manufacturing.
Innovation Solution
A level shift circuit design that includes a first voltage domain circuit, a middle voltage domain circuit, and a second voltage domain circuit, where signals are switched between high and low level voltages, ensuring that voltage changes across transistors remain within safe thresholds, preventing transistor breakdown during voltage domain conversions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common ground terminal is provided to different voltage domains, then the level shift circuit can convert signals between voltage domains, but transistors break down when voltage differences exceed their withstand threshold
Solution Approach 1:
The patent introduces a third voltage domain as an intermediary between the first and second voltage domains. The level shift circuit is divided into a first level shift circuit (first to third domain) and a second level shift circuit (third to second domain). This intermediary voltage domain acts as a mediator that breaks down the direct high-voltage difference path into two smaller voltage difference paths, preventing transistor breakdown while maintaining signal conversion functionality.
Solution Approach 2:
The patent segments the level shift circuit into two separate level shift circuits: a first level shift circuit converting signals from the first voltage domain to the third voltage domain, and a second level shift circuit converting signals from the third voltage domain to the second voltage domain. This segmentation divides the single large voltage difference into two smaller voltage differences, ensuring each transistor operates within its withstand threshold while achieving the overall voltage domain conversion.
2Reliability
If transistors with higher withstand threshold voltage are used, then transistor breakdown is prevented, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the voltage domain parameters by introducing a third voltage domain with intermediate voltage levels. Instead of relying on transistors with higher withstand thresholds, the system modifies the operating voltage parameters of the level shift circuit by adding an intermediate domain, thereby keeping standard transistors within their safe operating ranges while achieving the required voltage conversion.
3Productivity
If voltage conversion is performed directly between first and second voltage domains, then signal conversion efficiency is high, but transistors are exposed to excessive voltage differences
Solution Approach 1:
The third voltage domain serves as an intermediary that enables signal conversion between the first and second voltage domains while protecting transistors from excessive voltage differences. The first level shift circuit converts signals from the first domain to the third domain, and the second level shift circuit converts signals from the third domain to the second domain, maintaining conversion efficiency while ensuring transistor safety through the intermediary voltage domain.
Data Source
AI summary
A level shift circuit converts input signals in a first voltage domain into output signals in a second voltage domain. The level shift circuit includes a first voltage domain circuit, a middle voltage domain circuit, and a second voltage domain circuit. The middle voltage domain circuit convert the signals in the first voltage domain received by the first voltage domain circuit into signals in a middle voltage domain. The second voltage domain circuit converts the signals in the middle voltage domain into signals in the second voltage domain and outputs the converted signals. The signals in the middle voltage domain are partly different from the signals in the first voltage domain and the second voltage domain. Each signal in the first voltage domain is different from the signals in the second voltage domain. A display apparatus is also disclosed.