Cascaded Level Shifter With Voltage-Divider Biasing
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Solution Overview
Problem
Existing level shifters face challenges in increasing the shift range of output signals across different voltage domains, which is essential for circuits requiring diverse voltage levels.
Innovation Solution
The proposed level shifter incorporates a buffer circuit, a first shift circuit with a voltage divider circuit providing inner bias to stacking transistors, and a second shift circuit, allowing for increased voltage differences between input and output domains by utilizing a first voltage divider circuit and a second voltage divider circuit to generate control signals efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional level shifter is used to shift voltage domains, then the circuit can operate at different voltage levels, but the shift range of the output signal is limited
Solution Approach 1:
The level shifter is divided into multiple independent shift circuits (first shift circuit and second shift circuit), each responsible for a specific voltage domain transition. This segmentation allows each circuit to be optimized for its specific function while collectively achieving a broader overall shift range, resolving the contradiction between adaptability and signal shift range.
Solution Approach 2:
The patent extends the voltage shift operation from a single-dimensional approach to a multi-dimensional approach by implementing cascaded shift circuits that operate in series. The first shift circuit handles the initial voltage domain transition, and the second shift circuit further extends the shift range, effectively adding a temporal and functional dimension to the voltage shifting process, thereby achieving both adaptability and extended shift range.
2Area of stationary object
If the circuit area for generating control signals is reduced, then integration density increases, but control signal generation becomes more challenging
Solution Approach 1:
The voltage divider circuits are merged with the shift circuit structures, eliminating the need for separate control signal generation blocks. The voltage dividers directly generate the required control signals as part of their voltage scaling function, thereby reducing overall circuit area while maintaining manageable complexity through functional integration.
Solution Approach 2:
The voltage divider circuits serve multiple functions: they scale down voltages for proper logic level translation and simultaneously generate the control signals needed for the shift circuit operation. This multi-functionality reduces the need for dedicated control signal generation circuitry, decreasing overall circuit area while keeping the design manageable.
3Area of stationary object
If voltage divider circuits are used to generate control signals, then circuit area is reduced, but voltage division precision must be maintained
Solution Approach 1:
The patent carefully selects and adjusts the resistance values in the voltage divider circuits to achieve precise voltage division ratios. By optimizing these parameters during design, the circuits maintain accurate voltage scaling and control signal generation while occupying minimal area, thus resolving the contradiction between compactness and precision.
Solution Approach 2:
The voltage divider circuits are designed to automatically generate the appropriate control signals based on the input voltage levels without requiring external calibration or adjustment mechanisms. This self-service capability ensures consistent voltage division precision while maintaining a compact area, as no additional precision-tuning circuitry is needed.
Data Source
AI summary
A level shifter includes a buffer circuit, a first shift circuit, and a second shift circuit. The buffer circuit provides a first signal and a first inverted signal to the first shift circuit, such that the first shift circuit provides a second signal and a second inverted signal to the second shift circuit. The second shift circuit generates a plurality of output signals according to the second signal and the second inverted signal. The first shift circuit includes a plurality of first stacking transistors and a first voltage divider circuit. The first voltage divider circuit is electrically coupled between a first system high voltage terminal and a system low voltage terminal. The first voltage divider circuit is configured to provide a first inner bias to gate terminals of the first stacking transistors.