Flip-Flop Shadow Latch Timing Monitoring in Integrated Circuits
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Solution Overview
Problem
Integrated circuits face functionality failures due to signals not being passed within tight timing windows, leading to potential failures if delays exceed the timing buffer, which can be caused by variations during fabrication or aging, resulting in improper operation.
Innovation Solution
A detection circuit utilizing a single detection latch and logic gate to monitor timing signals, with a delay element acting as a buffer to detect approaching timing failures before they occur, allowing for proactive measures to prevent failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signals are passed through flip-flops and logic circuits with tight timing windows, then proper circuit functionality is maintained, but timing failures occur when delays exceed the timing buffer due to fabrication variations or aging
Solution Approach 1:
The detection circuit performs preliminary monitoring of signal delays through a shadow path with matching delay characteristics. By detecting timing violations before they cause functional failures, the system can take corrective actions such as adjusting clock frequencies or reconfiguring circuits to prevent timing failures from occurring
Solution Approach 2:
The detection circuit continuously monitors actual signal delays and provides feedback about timing buffer status. This feedback mechanism allows the system to detect when delays are approaching critical thresholds and take corrective actions to maintain proper timing margins, resolving the contradiction between maintaining functionality and preventing timing buffer exhaustion
2Reliability
If a detection circuit is added to monitor timing signals, then timing failures can be detected before they occur, but device complexity increases
Solution Approach 1:
The detection circuit uses a shadow path that replicates the critical signal path through equivalent logic elements and delay components. This copy allows monitoring of timing characteristics without significantly increasing overall circuit complexity, as the shadow path reuses similar structures already present in the design
Solution Approach 2:
The detection circuit is designed to monitor multiple timing paths simultaneously using shared detection resources. The same detection latch and comparison logic can monitor different critical paths by reconfiguring the shadow path, reducing overall complexity compared to having separate detection circuits for each path
Data Source
AI summary
An integrated circuit includes a data propagation path including a flip-flop. The flip-flop includes a first latch and a second latch. The integrated circuit includes a third latch that acts as a dummy latch. The input of the third latch is coupled to the output of the first latch. The integrated circuit includes a fault detector coupled to the output of the flip-flop and the output of the third latch. The third latch includes a signal propagation delay selected so that the third latch will fail to capture data in a given clock cycle before the second latch of the flip-flop fails to capture the data in the given clock cycle. The fault detector that detects when the third latch is failed to capture the data.