Adaptive Read Signal Pulse Width Control for Electrical Fuse Reliability
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Solution Overview
Problem
The read access time of an electrical fuse varies due to PVT variations, leading to excessive electrical stress and reduced cumulative number of read accesses, as existing methods set the width of the read signal pulse loosely, resulting in longer exposure to read current than necessary.
Innovation Solution
A circuit design where a transistor is turned off after sensing a logical value, reducing the time the electrical fuse is subjected to read current stress, and a control circuit regulates the pulse width to minimize electrical stress, thereby increasing the cumulative number of read accesses from 2 million to 200 million.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of the read signal pulse is set loosely to cover PVT variations, then the read access time increases, but the electrical stress on the fuse increases and the cumulative number of read accesses decreases
Solution Approach 1:
The patent applies dynamics by making the read signal pulse width adaptive rather than fixed. The control circuit dynamically adjusts the pulse width based on feedback from the fuse's actual resistance value, allowing the system to optimize between read access time and electrical stress for each individual fuse instance, thereby resolving the contradiction between reliability and electrical stress.
Solution Approach 2:
The patent implements feedback by measuring the actual resistance of the fuse during the read operation and using this information to adjust the read signal pulse width. The control circuit monitors the fuse's electrical characteristics and modifies the pulse duration accordingly, ensuring that the fuse is exposed to read current for exactly the time needed, thus reducing unnecessary electrical stress while maintaining reliable reading.
2Reliability
If the read signal pulse width is increased to ensure reliable reading across PVT variations, then the read access time increases, but the fuse is subjected to electrical stress longer than necessary
Solution Approach 1:
The system dynamically adjusts the read signal pulse width based on the actual fuse resistance measured during operation. Instead of using a fixed conservative pulse width that works for all PVT conditions, the control circuit adapts the pulse duration to match the specific fuse's characteristics, achieving reliable reading with minimal time exposure.
Solution Approach 2:
The patent changes the temporal parameter (pulse width) of the read signal based on the electrical parameter (fuse resistance) being measured. By varying the pulse width according to the fuse's actual state, the system optimizes the balance between ensuring reliable detection and minimizing the time the fuse is exposed to stress current.
3Measurement precision
If a higher read voltage is used to improve signal detection, then the reading accuracy improves, but the electrical stress on the fuse worsens
Solution Approach 1:
The patent uses periodic action by applying the read voltage in controlled pulses rather than continuously. The read voltage is applied only for the specific duration needed to measure the fuse resistance, then turned off. This pulsed approach allows sufficient voltage for accurate measurement while limiting the total time exposure to electrical stress.
Solution Approach 2:
The system dynamically controls both the voltage application timing and the pulse width based on real-time feedback. The read voltage is applied at the optimal moment and for the optimal duration determined by the fuse's actual characteristics, achieving high measurement precision while minimizing cumulative electrical stress through adaptive temporal control.
Data Source
AI summary
A circuit includes a fuse circuit and a control circuit. The fuse circuit has an electrical fuse. The control circuit is configured to receive an input signal having an input pulse, and, based on a feedback signal from the fuse circuit, generates a read pulse smaller than the input pulse for use in reading the data stored in the electrical fuse.