Multi-Stage Level Shifter for High-Voltage Output Swing
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Solution Overview
Problem
Semiconductor devices face challenges in generating output signals with higher swing levels while operating with low power supply voltages, leading to increased manufacturing complexity and costs due to the need for elements capable of handling higher voltages, which complicates the manufacturing process and increases costs.
Innovation Solution
A level shifter is implemented with semiconductor elements that receive a low-level power supply voltage and generate output signals with higher levels using multiple stages of elements receiving progressively higher power supply voltages, allowing the use of elements with the same gate insulating layer thickness and reducing manufacturing difficulty and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If semiconductor elements are designed to handle higher output voltage levels, then output signal swing level is improved, but manufacturing complexity and cost increase due to requiring thicker or larger gate insulating layers
Solution Approach 1:
The level shifter is divided into multiple stages, where each stage handles a portion of the voltage translation. The first stage translates the input signal from a first voltage level to a second voltage level, and the second stage translates from the second voltage level to a third voltage level. This segmentation allows each stage to use semiconductor elements with gate insulating layers designed for lower voltage stress, avoiding the need for thick gate insulating layers in the entire circuit while achieving high output swing levels.
Solution Approach 2:
The patent introduces intermediate voltage levels (second voltage level) as mediators between the input (first voltage level) and output (third voltage level). By using buffer circuits at intermediate stages that operate at lower voltage levels, the semiconductor elements only need to withstand the voltage differences at their respective stages rather than the full output swing, enabling the use of thinner gate insulating layers throughout the circuit.
2Use of energy by moving object
If semiconductor elements with thicker gate insulating layers are used to handle higher voltages, then output signal swing level is improved, but device complexity and integration difficulty increase
Solution Approach 1:
The voltage translation function is segmented across multiple stages, with each stage handling a limited voltage range. This allows all semiconductor elements in the circuit to use gate insulating layers of the same thickness, as no single element needs to withstand the full output voltage swing. The segmentation eliminates the need for mixed-thickness gate insulating layers, simplifying device fabrication and integration.
Solution Approach 2:
The patent changes the voltage level parameters at each stage of the level shifter. The first stage operates with voltage levels between the first and second voltage levels, while the second stage operates between the second and third voltage levels. This parameter change approach ensures that the voltage stress on semiconductor elements at any stage does not exceed the capabilities of elements with standard gate insulating layer thickness, thereby reducing device complexity.
3Device complexity
If a single-stage level shifter is used to achieve high output voltage levels, then circuit simplicity is improved, but manufacturing cost increases due to requiring specialized high-voltage elements
Solution Approach 1:
The level shifter is segmented into multiple identical or similar circuit stages. Each stage uses the same type of semiconductor elements with identical gate insulating layers, which can be manufactured using the same process parameters. This segmentation approach increases manufacturing yield and reduces costs compared to producing single-stage high-voltage elements, while maintaining relatively simple circuit architecture through repetition of standardized blocks.
Solution Approach 2:
The semiconductor elements used in each stage of the level shifter are universal in design, meaning the same element type and gate insulating layer thickness can be used throughout the entire circuit. This universality allows for standardized manufacturing processes and reduces the need for specialized high-voltage element fabrication, thereby reducing manufacturing costs while maintaining circuit simplicity through repeated use of the same building block.
Data Source
AI summary
A level shifter includes: an input circuit receiving an input signal swinging between a reference voltage and a first power supply voltage having a level higher than a level of the reference voltage; an output circuit outputting an output signal swinging between a second power supply voltage having a level higher than the level of the first power supply voltage and a third power supply voltage having a level higher than the level of the second power supply voltage; and a tolerant circuit connected between the input circuit and the output circuit, and configured to limit an output voltage of the input circuit to a range between the reference voltage and the second power supply voltage.