EP0161947A2
Expired / Lapsed
EP
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Integrated circuit having a fuse circuit
Assignee: Fujitsu Ltd
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Filing: 1985-02-28
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Granted: —
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Expires: 2005-02-28
Abstract
Abstract The fuse circuit comprises a fuse (F) and a transistor (Tr4) connected in series with an impedance element (Tr1, R) between a negative and a positive voltage supply sources (VSS, VDD). A potential (Vp) is generated at the junction point between the transistor (Tr4) and the impedance element (Tr1, R) and is applied to an inverter for indicating the fuse state. The impedance element including a transistor (Tr1) forms a constant-current source, and the internal resistance of transistor (Tr4) varies as a function of the fuse resistance. Due to the provision of the impedance element, a predetermined threshold resistor value can be provided which allows a correct detection of the fuse condition, even when the fuse is in "regrown fuse" or "grown-back" fuse state due to leakage between the fuse terminals after blowing of the fuse.
Inventors
- 👤 Tadayoshi Kunitoki
- 👤 Kunihiko Gotoh
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 00:43
CPC Classifications
G; G11; G11C; G11C17/00; G11C17/14; G11C17/16; G11C29/00; G11C29/02; G11C29/027; G11C5/00; G11C5/02; G11C5/025
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
150 words
Integrated circuit having a fuse circuit, comprising : first and second power supply means for supplying respectively a first voltage (V DD ) and a second voltage(V SS ); characterized by a first transistor (Tr4) having a gate, a source and a drain; a fuse (F) connected between the source of the first transistor and the second power supply means; and an impedance element means (Trl, R; Trl) is connected between the drain of the first transistor and said first power supply means; the first transistor (Tr4) having a higher on-state resistance when the fuse (F) is in the blown condition, compared to when the fuse is in the unblown condition, and a judging potential (V ) corresponding to the condition of the fuse being generated at the junction point between the first transistor (Tr4) and the impedance element means, for juding whether the fuse has been blown or not.
Claim 2
Dependent Claim
150 words
Integrated circuit having a fuse circuit, comprising : first and second power supply means for supplying respectively a first voltage (V DD ) and a second voltage(V SS ); characterized by a first transistor (Tr4) having a gate, a source and a drain; a fuse (F) connected between the source of the first transistor and the second power supply means; and an impedance element means (Trl, R; Trl) is connected between the drain of the first transistor and said first power supply means; the first transistor (Tr4) having a higher on-state resistance when the fuse (F) is in the blown condition, compared to when the fuse is in the unblown condition, and a judging potential (V ) corresponding to the condition of the fuse being generated at the junction point between the first transistor (Tr4) and the impedance element means, for juding whether the fuse has been blown or not.
Claim 3
Dependent Claim
18 words
Integrated circuit according to claim 1, characterized in that said first transistor (Tr4) is a depletion type transistor.
Claim 4
Dependent Claim
39 words
Integrated circuit according to any one of claims 1 and 2, characterized in that said impedance element means comprises a second transistor (Trl) having a constant current characteristic, said second transistor having a gate, a source and a drain.
Claim 5
Dependent Claim
54 words
Integrated circuit as claimed in claim 3, characterized in that said impedance element means further comprises a resistor (R) connected between the gate and the source of said second transistor (Trl), and said potential (V ) is generated at the junction point between said resistor (R) and the drain of the first transistor (Tr4).
Claim 6
Dependent Claim
27 words
Integrated circuit according to claim 4, characterized in that the resistance of the resistor (R) is equivalent to that of the fuse (F) in the unblown condition.
Claim 7
Dependent Claim
23 words
Integrated circuit according to any one of claims 3 to 5, characterized in that the second transistor (Trl) is a depletion type transistor.
Claim 8
Dependent Claim
31 words
Integrated circuit according to any one of claims 3 to 6, characterized in that the saturation current of the second transistor (Trl) is lower than that of the first transistor (Tr4).
Claim 9
Dependent Claim
45 words
Integrated circuit according to claim 3, characterized in that the ratio W/L of the first transistor (Tr4) is larger than that of the second transistor (Trl), where W is the channel width and L is the channel length of the gate electrode of each transistor.
Claim 10
Dependent Claim
28 words
Integrated circuit according to any one of the preceding claims, characterized in that the gate of said first transistor (Tr4) is connected to the second power supply means.
Claim 11
Dependent Claim
28 words
lO. Integrated circuit according to claim 1, characterized in that said first transistor is an enhancement type transistor having a gate to which a constant potential is applied.
References Cited (Backward Citations)
No citation records indexed.
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