| 摘要 |
A laser fuse comprising of a conventional laser fuse and an NMOS transistor. The two voltage source terminals of the fuse are connected to a low voltage and a high voltage respectively. A laser window is formed on the high voltage source terminal serving as a fuse-breaking port for a laser beam. The gate terminal of the NMOS transistor is connected to a position between the two input terminals of the fuse. One source/drain terminal of the NMOS transistor is connected to an input terminal while the other source/drain terminal of the NMOS transistor is connected to an output terminal. When the fuse is completely broken, the NMOS transistor is non-conductive because a voltage lower than the threshold voltage of the NMOS transistor is supplied to the gate terminal. Even if the fuse is only partially broken, resistance at the second voltage source is increased so much that the voltage at the gate terminal of the NMOS transistor is again lower than the threshold voltage. Therefore, the NMOS transistor remains in an open state and the output terminal will be unaffected by any voltage at the input terminal.
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