Low Voltage Efuse Programming Circuit Using SCR
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Solution Overview
Problem
Existing methods for programming electronic fuses in integrated circuits face challenges when operating under low voltage power supply conditions, as they often result in high power dissipation and potential damage to thin oxide transistors due to insufficient programming current and voltage.
Innovation Solution
A circuit utilizing a semiconductor controlled rectifier (SCR) is employed to program fuses, where the SCR maintains a low on-resistance state during programming, allowing most power dissipation to occur within the fuse rather than the programming circuitry, and using a boost circuit to generate a sufficient programming voltage when external power is not available.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fuse programming methods are used under low voltage conditions, then the programming can be performed, but high power dissipation occurs and thin oxide transistors may be damaged
Solution Approach 1:
The patent extracts the high-power programming current path from the thin oxide transistor circuitry by using a separate SCR-based programming circuit. The SCR is triggered to conduct the programming current through the fuse, isolating the thin oxide transistors from the high stress conditions during programming, thus preventing damage while maintaining low-voltage operation
Solution Approach 2:
The SCR acts as an intermediary device that mediates between the low-voltage power supply and the fuse programming requirement. It enables high current flow through the fuse during programming while maintaining low voltage operation, and provides a controlled path for power dissipation away from sensitive transistor components
2Reliability
If higher programming current is used to ensure reliable fuse programming, then programming reliability improves, but power dissipation increases and transistor damage risk increases
Solution Approach 1:
The patent segments the circuit into distinct functional regions: a programming circuit region containing the SCR and fuse, and a transistor circuit region. This segmentation allows the programming current to be confined to the fuse programming path without affecting the transistor region, enabling reliable programming while protecting transistors from harmful current stress
Solution Approach 2:
The patent converts the potentially harmful high programming current into a beneficial effect by directing it through the SCR-fuse path. The SCR's ability to handle high currents is used to program the fuse reliably, while the circuit design ensures this same current does not reach the transistors, thus converting what would be a harmful factor into a useful programming mechanism
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces power dissipation and minimizes stress on gate oxides, enabling efficient programming of fuses at low voltages with reduced risk of damage to transistors, while ensuring reliable operation and improved reliability by concentrating programming current through the SCR.
Implementation Method 1
the SCR maintains a low on-resistance state during programming, allowing most power dissipation to occur within the fuse rather than the programming circuitry
Implementation Method 2
A circuit utilizing a semiconductor controlled rectifier (SCR) is employed to program fuses, where the SCR maintains a low on-resistance state during programming
Data Source
AI summary
A circuit for programming a fuse is disclosed. The circuit includes a voltage supply terminal (Vf) and a semiconductor controlled rectifier (222, 224). The fuse is coupled between the voltage supply terminal and the semiconductor controlled rectifier. A switching circuit (200, 202, 208, 210) is coupled to the semiconductor controlled rectifier.