EP0122564A2
Expired / Lapsed
EP
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Read only memory
Assignee: Toshiba Corp
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Filing: 1984-04-06
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Granted: —
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Expires: 2004-04-06
Abstract
Abstract Data is read out from memory cells (M 11 - Mmn) in which "0" level and "1" level binary data have been stored, and a signal potential responsive to the readout data is compared with a comparison potential (VD) by a sense amplifier (SA), thereby sensing the data. In a comparison potential generator (20), the above comparison potential (VD) is set to have the intermediate potential between a potential (VBc) obtained by a dummy cell (Mc) in which the "1" level data has been stored, and a potential (VB d ) obtained by a dummy cell (M d ) in which the "0" level data has been stored.
Inventors
- 👤 Hiroshi Iwahashi
- 👤 Masamichi 308 Denenchofu-Sky-Heights Asano
- 👤 Hidenobu Minagawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 06:51
CPC Classifications
G; G11; G11C; G11C16/00; G11C16/02; G11C16/06; G11C16/26; G11C16/28
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
92 words
A read only memory comprising: memory cells (M 11 - M mn ) consisting of memory devices for storing data; comparison potential generating means (20) for generating such a comparison potential (VD) that its value varies responsive to a power potential and that the gradients of changes in the values before and after a predetermined power potential as a turning point differ; and data sense means (SA) for sensing said data by comparing a signal potential to be obtained when reading out the data from said memory cells with said comparison potential.
Claim 2
Dependent Claim
92 words
A read only memory comprising: memory cells (M 11 - M mn ) consisting of memory devices for storing data; comparison potential generating means (20) for generating such a comparison potential (VD) that its value varies responsive to a power potential and that the gradients of changes in the values before and after a predetermined power potential as a turning point differ; and data sense means (SA) for sensing said data by comparing a signal potential to be obtained when reading out the data from said memory cells with said comparison potential.
Claim 3
Dependent Claim
79 words
A read only memory according to claim 1, characterized in that said comparison potential generating means (20) generates a comparison potential (VD) between a first potential (V Bc ) which corresponds to one data in the binary data to be stored in said memory cells and which has a dependence upon the power potential and a second potential (VB d ) which corresponds to the other data in the binary data and which is dependent upon the power potential.
Claim 4
Dependent Claim
141 words
A read only memory according to claim I, characterized in that said comparison potential generating means (20) consists of: first potential generating means (30) for generating a first potential (VB c ) which corresponds to one data in the binary data to be stored in said memory cells and which has a dependence upon the power potential; second potential generating means (40) for generating a second potential (VB d ) which corresponds to the other data in the binary data to be stored in said memory cells and which has a dependence upon the power potential; and two impedance means (16, 17) applied to each terminal of said first and second potentials, respectively, and connected to the other terminals, wherein the comparison potential (VD) is generated from a connecting point of the other terminals of said two impedance means (16, 17).
Claim 5
Dependent Claim
45 words
A read only memory according to claim 3, characterized in that values of said two impedance means (16, 17) are set to generate the intermediate potential between said first potential (VB c ) and said second potential (VB d ) as the comparison potential (VD).
Claim 6
Dependent Claim
97 words
A read only memory according to claim 3, characterized in that said first potential generating means (30) has first dummy cells (M c , M e ) which are set into the memory state so that one data in the binary data to be stored in said memory cells is stored, and characterized in that said second potential generating means (40) has second dummy cells (M d . M f ) which are set into the memory state so that the other data in the binary data to be stored in said memory , cells is stored.
Claim 7
Dependent Claim
37 words
A read only memory according to claim 5, characterized in that said first and second dummy cells (M c , M d ) are both constituted by nonvolatile memory devices which are equivalent to said memory cells.
Claim 8
Dependent Claim
87 words
A read only memory according to claim 5, characterized in that said first and second dummy cells ( Mc , M d ) are both constituted by double-gate type MOS FETs each having a floating gate and a control gate, wherein either one of said first and second dummy cells is set into the memory state in that one data in said binary data is stored by applying a lower potential (V c - a) than the power potential (V c ) to the control gate thereof.
Claim 9
Dependent Claim
107 words
A read only memory according to claim 5, characterized in that said first and second dummy cells (M c ,M d ) are both constituted by double-gate type MOS FETs each having a floating gate and a control gate, and the first dummy cell (M c ) is set into the memory state in that one data in the binary data is stored when the floating gate is neutral, and characterized in that the second dummy cell (M d ) is set into the memory state in that the other data in the binary data is stored when the electrons are injected in the floating gate thereof.
Claim 10
Dependent Claim
52 words
A read only memory according to claim 7, characterized by further including means (50) for applying the potential (V c - a) which is lower than the power potential (V c ) to the control gate of either one of said first and second dummy cells (M c , M d ).
Claim 11
Dependent Claim
36 words
A read only memory according to claim 8, characterized by further including means (81 - 84, 85 - 87, G d ) for injecting the electrons in the floating gate of said second dummy cell (Md)
Claim 12
Dependent Claim
37 words
A read only memory according to claim 3, characterized by further including means (18, 19) for shifting a level of either one of said first potential ( VBc ) and said second potential (VB d ). ,
Claim 13
Dependent Claim
63 words
A read only memory according to claim 7, characterized by further including means (130) for further reducing the potential at the control gate of the dummy cell (M d ) of which a lower potential than the power potential (V c ) is applied to the control gate thereof when the data is written in said memory cells (Mil - M mn ).
References Cited (Backward Citations)
US4223394A
Cited
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