Level Shifter Output Stage With Current Limiting at Sub-Threshold Voltage
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Solution Overview
Problem
Level shifters fail to operate effectively at sub-threshold voltages due to leakage currents, limiting their functionality in low-power designs.
Innovation Solution
Incorporating current limiters, such as diode-connected MOSFETs, between switches in the level shifter to reduce current flow and enable successful voltage level adjustments, allowing operation with sub-threshold voltages by providing sufficient voltage drops and reducing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If level shifters are used to interface voltage signals between circuits operating with different power voltages, then voltage level conversion is achieved, but leakage currents cause operation failure at sub-threshold voltages
Solution Approach 1:
A current limiter circuit is introduced as an intermediary component between the level shifter and the output. This current limiter acts as a mediator that controls and restricts the leakage current flowing through the level shifter, enabling reliable operation at sub-threshold voltages while maintaining the voltage level conversion function. The current limiter includes a first current limiter circuit and a second current limiter circuit that work together to clamp the current to safe levels.
Solution Approach 2:
The invention changes the operating parameters of the level shifter by introducing current limiting functionality. By dynamically controlling the current parameter through the current limiter circuits, the system can operate reliably at sub-threshold voltages where conventional level shifters would fail due to excessive leakage currents. The current limiter adjusts the effective current parameter to match the reduced voltage operating conditions.
2Reliability
If current limiters are added to reduce leakage currents, then operation at sub-threshold voltages is enabled, but device complexity increases
Solution Approach 1:
The current limiter functionality is merged with the existing level shifter structure. The first and second current limiter circuits are integrated into the level shifter architecture, sharing common components and signal paths where possible. This merging approach enables current limiting without completely redesigning the level shifter, thus reducing the overall complexity increase compared to adding entirely separate current limiting circuits.
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
Enables the level shifter to successfully adjust voltage levels and operate effectively even at sub-threshold voltages, enhancing the device's driving ability and expanding its operational range.
Implementation Method 1
Incorporating current limiters, such as diode-connected MOSFETs, between switches in the level shifter to reduce current flow and enable successful voltage level adjustments
Implementation Method 2
providing sufficient voltage drops and reducing leakage currents
Data Source
AI summary
A device is disclosed that includes a level shifter and an output stage. The level shifter is configured to output a first output signal at a first output terminal in response to a first input signal having a first logic level, and is configured to output a second output signal at a second output terminal in response to the first input signal having a second logic level. The output stage is configured to receive and adjust the first output signal or the second output signal that is selected in response to the first input signal, and configured to generate a third output signal, wherein the third output signal has a logic value that is the same as a logic value of the first output signal or the second output signal.