Cross-Voltage Relief Level Shifter for Low-Voltage Inputs
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Solution Overview
Problem
Level shifters face challenges in supporting low input voltages due to the need for high-voltage transistors with higher threshold voltages, leading to potential malfunctions when input voltages are lower than the threshold voltage.
Innovation Solution
A level shifter design incorporating low-voltage transistors protected by cross-voltage relief circuits and optional pull-up circuits to manage high cross-voltages, ensuring reliable operation across varying voltage domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-voltage transistors with higher threshold voltages are adopted, then reliability is improved, but the ability to support low input voltages deteriorates
Solution Approach 1:
The patent introduces a level shifter circuit as an intermediary component between low-voltage input signals and high-voltage output circuits. This level shifter includes voltage translation circuits that convert low-voltage input signals to high-voltage signals, enabling low-voltage microcontrollers to control high-voltage loads without exposing low-voltage transistors to harmful high cross-voltages. The intermediary structure allows the system to use reliable high-voltage transistors for power control while maintaining compatibility with low-voltage control signals.
2Adaptability or versatility
If low-voltage transistors are used, then input voltage range is improved, but protection from high cross-voltages deteriorates
Solution Approach 1:
The patent segments the voltage control system into distinct voltage domains: a low-voltage control domain for signal processing and a high-voltage power domain for load control. Low-voltage transistors operate exclusively in the control domain where they are safe from high cross-voltages, while high-voltage transistors handle power switching. This segmentation allows low-voltage transistors to be used for their superior low-voltage performance without exposure to damaging high-voltage stress.
Solution Approach 2:
The level shifter acts as an intermediary barrier that isolates low-voltage transistors from high-voltage environments. It translates control signals from the low-voltage domain to the high-voltage domain, allowing low-voltage transistors to control high-voltage loads indirectly without being exposed to harmful high cross-voltages, thus protecting them while maintaining wide input voltage support.
3Device complexity
If conventional level shifter designs are used, then device complexity is reduced, but transition speed deteriorates
Solution Approach 1:
The patent employs dynamic voltage translation mechanisms where the level shifter circuit actively adjusts voltage levels based on input signal conditions. The voltage translation circuits use controlled switching and regenerative feedback mechanisms that accelerate transition speeds by providing strong drive currents during voltage level changes, while maintaining a relatively simple overall circuit structure through efficient use of standard transistor configurations.
Data Source
AI summary
A level shifter includes first and second transistors, first and second cross-voltage relief circuits, and third and fourth transistors. The first and second transistors are cross-coupled. First terminals of the first and second transistors receive a first high voltage, and second terminals of the first and second transistors output a first and second output voltages respectively. The first cross-voltage relief circuit provides a voltage drop between the first transistor and the third transistor, and the second cross-voltage relief circuit provides a voltage drop between the second transistor and the fourth transistor. The third and fourth transistors respectively receive the first and second input voltages that are complementary to each other. The first input voltage is at a second high voltage lower than the first high voltage or a low voltage lower than the second high voltage.