Adaptive Level Shifter for Floating-Node Stability in Sleep Mode
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Solution Overview
Problem
Conventional level shifters are not suitable for power-saving operation modes as they can cause circuit malfunctions due to floating nodes when the supply voltage is turned off, leading to voltage level inconsistencies between integrated circuits with different operating voltage swings.
Innovation Solution
A level shifter comprising a preliminary level-shifting circuit and an output auxiliary circuit that retains voltage levels using a buffer and auxiliary transistors, ensuring stable output signals even when the first supply voltage is turned off, preventing node floating and maintaining correct circuit operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the first supply voltage is turned off to enter power-saving operation mode, then power consumption is reduced, but the node A becomes floating and causes circuit malfunctions
Solution Approach 1:
The patent introduces a second auxiliary transistor (225) as an intermediary component connected between node A and ground. This transistor acts as a mediator that maintains node A's voltage level by providing a discharge path when the first supply voltage is turned off, preventing the floating state that would otherwise cause circuit malfunctions while enabling power-saving operation mode
Solution Approach 2:
The second auxiliary transistor (225) is pre-configured in the circuit during normal operation, standing by to activate when needed. When the first supply voltage is turned off, this transistor immediately becomes active to discharge node A and prevent floating, rather than requiring a reactive measure after the floating state occurs
2Adaptability or versatility
If conventional level shifter is used with different voltage swings, then voltage level conversion is achieved, but circuit malfunctions occur during power-saving mode due to floating nodes
Solution Approach 1:
The patent enhances the level shifter's universality by adding auxiliary transistors (223, 225) that serve dual functions: during normal operation, they remain inactive and do not interfere with standard level shifting; during power-saving mode, they activate to maintain voltage levels and prevent floating nodes. This allows the same circuit to reliably operate in both normal and power-saving modes
Data Source
AI summary
A level shifter adaptive for use in a power-saving operation mode is disclosed for interfacing two circuit units powered by a first supply voltage and a second supply voltage respectively. The level shifter includes a preliminary level shifting circuit and an output auxiliary circuit. With the aid of the two supply voltages, the preliminary level shifting circuit is employed to receive an input signal having a first operating voltage swing and functions to convert the input signal into a first output signal and a second output signal both having a second operating voltage swing. The first output signal and the second output signal have opposite voltage levels relative to each other. The output auxiliary circuit is utilized for retaining the voltage level of the first output signal based on the second supply voltage regardless of whether the level shifter is still powered by the first supply voltage or not.