Auxiliary-Stage Voltage Level Shifter for Sub-Threshold Transitions
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Solution Overview
Problem
Voltage level shifters face challenges in efficiently transitioning signals between domains with voltage levels below the threshold voltage of transistors, leading to prolonged state transitions due to sub-threshold conduction and partial conductivity issues.
Innovation Solution
Incorporation of auxiliary stages that detect mismatches between node states and input signals, supplying current to aid transitions, ensuring expedited state changes by facilitating the conductive state of transistors and removing supply voltage to accelerate transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If voltage level shifters operate with input signals below transistor threshold voltage, then interoperability between different voltage domains is achieved, but state transition duration is prolonged due to sub-threshold conduction
Solution Approach 1:
The auxiliary detection stages are activated in advance to monitor node transitions before they complete. When a node fails to transition properly due to sub-threshold conduction, the auxiliary stages detect this condition and immediately activate auxiliary transistors to force the transition, preventing prolonged stale states and ensuring timely completion of voltage level transitions.
2Speed
If auxiliary stages are added to detect and correct node transition failures, then state transition speed is improved, but device complexity increases
Solution Approach 1:
Auxiliary detection stages are introduced as intermediary components between the main level shifter nodes and the output. These stages monitor node states and activate auxiliary transistors only when needed, providing a mediation mechanism that accelerates transitions without permanently increasing the complexity of the main signal path. The auxiliary stages remain dormant during normal operation and only activate when transition failures are detected.
Data Source
AI summary
Provided is a voltage level shifter that operates in sub-threshold voltages. The level shifter includes a level shifting stage. The level shifting stage receives a first signal from a first voltage domain and outputs a second signal to a second voltage domain. The level shifter includes a first auxiliary stage. In response to the first signal having a first voltage level corresponding to a first logical state and a first node of the level shifting stage having a supply voltage level, the first auxiliary stage sources current to a second node of the level shifting stage. Sourcing the current to the second node accelerates a transition of the first node to a reference voltage. The level shifting stage outputs a second signal to a second voltage domain.