Multi-value read-only memory cell having an improved signal-to-noise ratio
First Claim
1. Multi-value read-only memory cell, having symmetrical construction for storing one of a first state and a second state and having asymmetrical construction for storing at least a third state, comprising:
- a MOS field-effect transistor having a source/drain region situated in a semiconductor body and having a drain/source region situated in the semiconductor body;
in order to store the first state, a first cell connection connected directly to the source/drain region of the MOS field-effect transistor and a second cell connection connected directly to the drain/source region of the MOS field-effect transistor;
in order to store the second state, the first cell connection connected via a first component to the source/drain region of the MOS field-effect transistor, and the second cell connection connected via a second component to the drain/source region of the MOS field-effect transistor;
in order to store the third state, the first cell connection connected via the first component to the source/drain region of the MOS field-effect transistor, and the second cell connection connected directly to the drain/source region of the MOS field-effect transistor;
in order to store a fourth state, the first cell connection connected directly to the source/drain region of the MOS field-effect transistor, and the second cell connection connected via the second component to the drain/source region of the MOS field-effect transistor;
a third cell connection connected to a gate electrode of the MOS field-effect transistor, the gate electrode being electrically insulated from the semiconductor body by an insulation layer (ISO); and
the first component being a first diode and the second component being a second diode.
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Accused Products
Abstract
The invention concerns a multi-valued read-only storage location which is constructed symmetrically for storing a first or second state (M, M"'"'"') and asymmetrically for storing at least a third state (M'"'"', M"). The advantage thereof is above all that the storage capacity is doubled without notably increasing expenditure and without impairing the signal-to-noise ratio with respect to conventional storage locations. The invention is suitable for electrically programmable and mask-programmable read-only memories, in particular for those used in low voltage technology.
167 Citations
3 Claims
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1. Multi-value read-only memory cell, having symmetrical construction for storing one of a first state and a second state and having asymmetrical construction for storing at least a third state, comprising:
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a MOS field-effect transistor having a source/drain region situated in a semiconductor body and having a drain/source region situated in the semiconductor body; in order to store the first state, a first cell connection connected directly to the source/drain region of the MOS field-effect transistor and a second cell connection connected directly to the drain/source region of the MOS field-effect transistor; in order to store the second state, the first cell connection connected via a first component to the source/drain region of the MOS field-effect transistor, and the second cell connection connected via a second component to the drain/source region of the MOS field-effect transistor; in order to store the third state, the first cell connection connected via the first component to the source/drain region of the MOS field-effect transistor, and the second cell connection connected directly to the drain/source region of the MOS field-effect transistor; in order to store a fourth state, the first cell connection connected directly to the source/drain region of the MOS field-effect transistor, and the second cell connection connected via the second component to the drain/source region of the MOS field-effect transistor; a third cell connection connected to a gate electrode of the MOS field-effect transistor, the gate electrode being electrically insulated from the semiconductor body by an insulation layer (ISO); and the first component being a first diode and the second component being a second diode. - View Dependent Claims (2)
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3. A multi-value read-only memory cell, having symmetrical construction for storing a first state and a second state and having asymmetrical construction for storing at least a third state, comprising:
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a MOS field-effect transistor having a source/drain region situated in a semiconductor body and having a drain/source region situated in the semiconductor body; in order to store the first state a first cell connection connected directly to the source/drain region of the MOS field-effect transistor, and a second cell connection connected directly to the drain/source region of the MOS field-effect transistor; in order to store the second state, the first cell connection connected via a first component to the source/drain region of the MOS field-effect transistor and the second cell connection connected via a second component to the drain/source region of the MOS field-effect transistor; in order to store the third state, the first cell connection connected via the first component to the source/drain region of the MOS field-effect transistor, and the second cell connection connected directly to the drain/source region of the MOS field-effect transistor; in order to store a fourth state, the first cell connection connected directly to the source/drain region of the MOS field-effect transistor, and the second cell connection connected via the second component to the drain/source region of the MOS field-effect transistor; a third cell connection connected to a gate electrode of the MOS field-effect transistor, the gate electrode being electrically insulated from the semiconductor body by an insulation layer; and the first component being a first resistor and the second component being a second resistor.
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Specification