Safe State Circuit Gating for Level Shifter Power Detection
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Solution Overview
Problem
Level shifters in integrated circuits fail to function properly if power is not fully present in the logic domain originating the signal, leading to communication issues between different logic domains.
Innovation Solution
A safe state circuit is used for logic domain power-on detection, which gates the level shifter's output when power is not properly supplied, ensuring proper communication and simplifying inter-domain logic validation with low power consumption and compact silicon area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If level shifters are used to facilitate communication between different logic domains, then signal communication between domains is improved, but the circuit fails to function properly if power is not fully present in the originating logic domain
Solution Approach 1:
The power detection circuit performs preliminary detection of power availability in the logic domain before enabling level shifter operation. The circuit monitors voltage levels and generates detection signals that gate the level shifter output, preventing improper operation before it can occur. This advance detection and gating mechanism ensures the level shifter only operates when power is fully present, resolving the reliability issue while maintaining communication functionality.
2Reliability
If safe state circuits are added for power-on detection and level shifter gating, then reliability under partial power conditions is improved, but device complexity increases
Solution Approach 1:
The power detection circuit is merged with the existing level shifter structure, sharing common transistors and circuit elements. The detection circuit utilizes the same transistor network that forms the level shifter, combining two functions (power detection and level shifting) into a single integrated structure. This merging approach improves reliability through power-on detection while minimizing the increase in device complexity by reusing existing circuit components.
3Reliability
If traditional power detection circuits are used, then power-on detection function is achieved, but current consumption and silicon area increase
Solution Approach 1:
The power detection circuit serves itself by utilizing the inherent electrical characteristics of the logic domain voltage without requiring external power sources or additional active components. The circuit passively monitors voltage levels through its transistor network, using the domain's own power conditions to drive the detection mechanism. This self-service approach enables power-on detection while minimizing current consumption, as the circuit draws negligible current during normal operation.
Data Source
AI summary
An Integrated Circuit (IC) as described herein may include a first logic circuit, a second logic circuit coupled to the first logic circuit via a level shifter, and a safe state circuit coupled to the first logic circuit and to a first input of a logic gate. For example, a second input of the logic gate may be coupled to an output of the level shifter, and an output of the logic gate may be coupled to the second logic circuit. The safe state circuit may further include a front-end portion; a reversible current mirror portion coupled to the front-end portion; and a voltage-level translation portion coupled to the reversible current mirror portion.