Level Shifter State Reinforcement for Below-Ground Supply Stability
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Solution Overview
Problem
Low-to-high voltage level shifters face issues with maintaining logical states of output signals when the first supply voltage falls below ground, leading to undesirable voltage changes and logical state switches in output signals.
Innovation Solution
Incorporating a state reinforcement circuit that provides additional signal paths to reinforce the logical states of output signals, ensuring they remain stable even when the first supply voltage drops below ground and returns, using transistors and diodes connected to a second supply voltage to maintain the logical states of output signals A and B.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a low-to-high voltage level shifter is used to shift voltage levels, then voltage level conversion is achieved, but the logical state of output signals becomes unstable when the first supply voltage falls below ground
Solution Approach 1:
A state reinforcement circuit is introduced as an intermediary component between the level shifter and the output signals. This circuit includes transistors and diodes that actively reinforce the logical state of output signals, preventing unintended state changes when the first supply voltage fluctuates below ground. The state reinforcement circuit acts as a mediator that isolates the output signals from the harmful voltage fluctuations.
Solution Approach 2:
The state reinforcement circuit provides beforehand cushioning by preparing protective pathways before voltage fluctuations occur. When the first supply voltage drops below ground, the diodes and transistors in the state reinforcement circuit are already in position to clamp or maintain the output signals at their correct logical levels, preventing the harmful voltage changes from affecting the output signals.
2Adaptability or versatility
If the first supply voltage is allowed to fluctuate below ground, then operational flexibility is maintained, but unintended logical state switches occur in output signals
Solution Approach 1:
The state reinforcement circuit serves as an intermediary that decouples the output signals from the first supply voltage fluctuations. The circuit includes transistors whose gates are controlled by the output signals of the level shifter, and diodes that clamp the drain voltages to prevent them from following the supply voltage when it drops below ground. This intermediary structure allows the supply voltage to fluctuate while maintaining stable output signal logical states.
3Reliability
If additional state reinforcement circuit components are added, then logical state stability is improved, but device complexity increases
Solution Approach 1:
The state reinforcement circuit applies local quality by targeting only the specific nodes in the circuit that are susceptible to voltage fluctuations. Rather than redesigning the entire level shifter, the invention adds localized protection circuits at the output nodes where transistors and diodes are strategically placed to reinforce only the critical logical states that need protection, minimizing the overall complexity increase.
Data Source
AI summary
In one aspect, an integrated circuit (IC) includes a level shifter configured to generate a first output signal and a second output signal, and to receive an input voltage, a first supply voltage and a second supply voltage; and a state reinforcement circuit configured to maintain a logical state of the second output signal in response to the first supply voltage having a voltage below ground and the input voltage is logical high. If the input voltage is logical high, then the first output signal is logical low and the second output signal is logical high; and, if the input voltage is logical low, the first output signal is logical high and the second output signal is logical low.