Fault-Sensing Ring Oscillator Circuit for Stuck-At Fault Detection
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Solution Overview
Problem
Testing each ring oscillator in large semiconductor circuits to detect stuck-at-fault conditions is impractical due to their numerousness, affecting power characterization and device performance.
Innovation Solution
A fault-sensing ring oscillator circuit is configured with an enable circuit, an OR circuit, and a fault detection latch, where the OR circuit's output indicates active oscillators, and the latch sets a stuck-at-fault condition when oscillators are disabled but still active, allowing for quick detection of faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual testing of each ring oscillator is performed to detect stuck-at-fault conditions, then measurement precision is improved, but device complexity and time consumption increase significantly
Solution Approach 1:
The patent combines multiple ring oscillator outputs into a single OR circuit output. The OR circuit aggregates the states of all ring oscillators, allowing fault detection across the entire array through a single test point rather than requiring individual testing of each oscillator. This merging approach maintains measurement precision while dramatically reducing device complexity.
Solution Approach 2:
The enable circuit serves multiple functions: it controls the operational state of all ring oscillators simultaneously, provides a reset signal to the latch, and enables fault detection without requiring separate control circuits for each oscillator. This multi-functionality reduces the overall testing circuit complexity while maintaining comprehensive fault detection capability.
2Measurement precision
If individual testing of each ring oscillator is performed to detect stuck-at-fault conditions, then measurement precision is improved, but time consumption increases significantly
Solution Approach 1:
The OR circuit combines the outputs of all ring oscillators into a single signal that feeds the latch. This allows the system to detect faults across the entire ring oscillator array in a single operation rather than requiring sequential individual testing, thereby maintaining measurement precision while dramatically reducing the time required for fault detection.
Solution Approach 2:
The enable circuit is configured to disable all ring oscillators before the OR circuit evaluates their states. This preliminary action ensures that any active state detected by the OR circuit and latch must be a stuck-at-fault condition rather than normal operation, enabling rapid fault detection without requiring individual oscillator testing.
3Adaptability or versatility
If a large number of ring oscillators are used to improve circuit functionality, then adaptability is improved, but power consumption increases and fault detection becomes more difficult
Solution Approach 1:
The patent extracts the fault detection function from the operational function of the ring oscillators. The enable circuit selectively disables ring oscillators during normal operation, separating their functional use from their fault detection role. This allows the system to maintain adaptability with large numbers of oscillators while reducing power consumption by disabling them when not needed for fault detection.
Solution Approach 2:
The enable circuit periodically enables and disables the ring oscillators to facilitate fault detection at specific intervals. During normal operation, oscillators are enabled for functional use; at detection intervals, they are disabled so the OR circuit can evaluate their states. This periodic action allows the system to maintain both adaptability and controlled power consumption.
4Adaptability or versatility
If a large number of ring oscillators are used to improve circuit functionality, then adaptability is improved, but difficulty of detecting and measuring faults increases
Solution Approach 1:
The OR circuit merges the outputs of all ring oscillators into a single signal that directly controls the latch. This consolidation allows the system to maintain adaptability with large numbers of oscillators while simplifying fault detection to a single binary state (latch set or not set), thereby dramatically reducing the difficulty of detecting and measuring faults across the entire array.
Data Source
AI summary
Configuring a fault-sensing ring oscillator circuit is disclosed. In a particular embodiment, a fault-sensing ring oscillator circuit includes a plurality of ring oscillators; an enable circuit configured to enable and disable the plurality of ring oscillators; an OR circuit including a plurality of inputs, wherein each input is coupled to a respective ring oscillator of the plurality of ring oscillators; and a first fault detection latch including a SET input coupled to a first output of the OR circuit and a RESET input coupled to the enable circuit, wherein the first fault detection latch indicates a stuck at fault condition when the plurality of ring oscillators are disabled by the enable circuit and at least one of the plurality of ring oscillators is active.