Low-Voltage Level Shifter With Intermediate Stage Protection
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Solution Overview
Problem
Low voltage level shifters face challenges in operating effectively when the active voltage level of the input signal is below the threshold voltage of switching devices, leading to power consumption issues and potential device breakdown due to excessive voltage stress on core transistors.
Innovation Solution
Incorporating an intermediate stage with specific transistor configurations and voltage regulation mechanisms to manage the voltage applied to core transistors, ensuring the drain-to-source voltage does not exceed the maximum rating, and using core FETs with smaller threshold voltages and gate oxide thickness for low voltage switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the supply voltage of core components is lowered to reduce power consumption, then power consumption is reduced, but the input signal level decreases causing switching devices to turn off even when the input signal is in an active logic state
Solution Approach 1:
The patent introduces an intermediate stage between the input stage and output stage that acts as a mediator. This intermediate stage includes transistors whose gates are connected to the input signal and whose drains connect to the output stage. The intermediate stage boosts the low voltage input signal to a level sufficient to drive the output stage transistors, enabling reliable switching operation even when the core logic operates at reduced voltage levels for lower power consumption.
2Use of energy by moving object
If the active voltage level of the input signal is below the threshold voltage of switching devices, then power consumption is reduced, but the switching devices receiving the input signal are not turned on despite the active logic state
Solution Approach 1:
The intermediate stage serves as a voltage booster that receives the low voltage input signal below the threshold voltage of the output stage transistors and generates a higher voltage signal capable of properly activating the output stage switching devices. This allows the system to operate with low power consumption at the input while maintaining ease of operation at the output.
Solution Approach 2:
The patent changes the voltage parameter through the intermediate stage. The intermediate transistors are configured to amplify or boost the voltage level of the input signal, transforming it from a low voltage level (insufficient to turn on output transistors) to a higher voltage level (sufficient to drive the output stage), thereby maintaining switching device activation capability while allowing low voltage operation.
Data Source
AI summary
A level shifter circuit for low power applications that can shift the level of a digital signal that is below the threshold voltage of output transistors. The level shifter uses core transistors in the input stage and includes an intermediate stage that limits the voltage applied to the drain of the core transistors. The intermediate stage may include two transistors whose gate is connected to a reference voltage and turns off when the voltage at their source is equal to a threshold voltage below the reference voltage, thus limiting the maximum voltage applied to the transistors present in the input stage.