Capacitive Dynamic Level Shifter With DC Isolation and Low Delay
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Solution Overview
Problem
Conventional level shifters in power management systems face challenges such as DC consumption, high propagation delay, restricted power voltage domains, lack of DC isolation, asymmetrical signal transitions, and over-voltage stress, especially when input and output voltage domains are not related.
Innovation Solution
A dynamic bi-directional level shifter circuit utilizing metal-insulator-metal capacitors and cross-coupled latches, enabling flexible power domains with no DC consumption, fast operation, and symmetrical signal transitions, while avoiding high-voltage devices and maintaining operation across varying voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional level shifters are used to convert signals between different voltage domains, then level shifting function is achieved, but DC consumption occurs and propagation delay increases
Solution Approach 1:
The patent employs dynamic switching mechanisms that activate level shifting operations only during signal transitions rather than continuously. The circuit uses clocked switches and transmission gates that enable signal transfer periodically during active edges, eliminating continuous DC consumption while maintaining reliable level shifting functionality when needed.
Solution Approach 2:
The invention introduces dynamic control elements including clocked switches, transmission gates, and latch circuits that adapt the level shifter's operation to actual signal conditions. These dynamic components enable the circuit to switch between active and standby states, reducing DC consumption while maintaining operational reliability through controlled activation during signal transitions.
2Reliability
If conventional level shifters are used, then level shifting is achieved, but propagation delay is high
Solution Approach 1:
The level shifter circuit is divided into multiple functional stages including differential input stages, intermediate buffering stages, and output stages. Each stage is optimized for specific functions, allowing signal processing to be distributed across multiple smaller, faster operations rather than a single long delay path, thereby reducing overall propagation delay while maintaining reliable level shifting.
Solution Approach 2:
The patent introduces intermediate buffering stages and latch circuits between the input and output of the level shifter. These intermediary elements prepare signals for the next stage, providing signal conditioning and level preparation that reduces the burden on subsequent stages, thereby reducing overall propagation delay while ensuring reliable operation across voltage domains.
3Adaptability or versatility
If conventional level shifters are used, then level shifting between voltage domains is achieved, but power voltage domains are restricted
Solution Approach 1:
The patent designs a universal level shifter architecture that can operate across multiple voltage domains through differential signaling and controlled switching mechanisms. The circuit uses voltage-independent differential pairs and controlled switches that adapt to different supply voltages, enabling the same circuit to function reliably across various power voltage domains without requiring domain-specific design modifications.
Solution Approach 2:
The invention employs differential signaling parameters and switching control parameters that can be adjusted to match different voltage domain requirements. By changing operating parameters such as differential voltage levels, switch timing, and bias conditions, the level shifter adapts to various power voltage domains while maintaining reliable operation through parameter optimization for each domain configuration.
4Reliability
If conventional level shifters are used, then level shifting is achieved, but DC isolation between power domains is not maintained
Solution Approach 1:
The patent introduces AC-coupled intermediate stages including capacitive coupling elements and AC-coupled buffers between power domains. These intermediary components block DC voltage differences between power domains while allowing AC signal transmission, thereby maintaining DC isolation and preventing harmful DC coupling effects while enabling reliable level shifting operation across isolated voltage domains.
5Reliability
If conventional level shifters are used, then level shifting is achieved, but signal transitions are asymmetrical causing distortion
Solution Approach 1:
The patent deliberately introduces asymmetrical pre-distortion elements in the signal path that compensate for inherent asymmetries in the level shifting process. By applying asymmetrical compensation techniques such as differential pre-emphasis or asymmetrical switching timing, the circuit counteracts distortion effects and achieves symmetrical overall signal transitions, improving signal integrity and ease of operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves efficient level shifting with low propagation delay, unrestricted power domains, DC isolation, and reduced over-voltage stress, ensuring continuous operation even when input and output voltage domains are not related, as demonstrated by simulation results.
Implementation Method 1
A dynamic level shifter comprises two level shifting capacitors, each having a first terminal and a second terminal
Data Source
AI summary
A level shifter does not require any DC (standby) current consumption and has a fast operation with low propagation delay. The level shifting from input to output voltage ranges is performed by a pair of level shifting capacitors. The input-output power voltages domains are unrestricted and flexible. DC isolation is deployed between power domains. Symmetrical rise/fall times are without duty cycle distortion. Over voltage stress is reduced by using metal capacitors. Finally the level shifter does not use high-voltage devices for level shifting purpose. Embodiments of level shifters provide one-way level shifting and bi-directional level shifting.