Coded modulation for digital storage in analog memory devices
First Claim
1. A method of storing information bits in an analog memory device, the device including a plurality of analog memory cells, the method comprising the steps of:
- coding at least a portion of a given set of b of the information bits to generate a corresponding set of coded bits including more than b bits, such that the portion of the information bits subject to the coding is transformed into corresponding coded bits in the set of coded bits;
mapping the set of coded bits to one or more corresponding levels; and
storing each of the one or more levels in one of the analog memory cells;
wherein the mapping step is configured to provide at least one of;
(i) an increase in an effective storage capacity of at least a subset of the analog memory cells; and
(ii) a decrease in a readout error probability of at least a subset of the analog memory cells;
relative to an effective storage capacity and a readout error probability associated with storage of unmapped analog levels in the analog memory cells.
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Accused Products
Abstract
Digital data is stored in an analog memory device using coded modulation techniques. The memory device includes a number of memory cells, each capable of storing one of a number of different levels. A given set of b information bits to be stored in the memory device is first coded in a convolutional or block coder to generate a set of coded bits which includes more than b bits. The set of coded bits is then mapped to one or more corresponding levels, and the one or more levels are each stored in a separate cell of the memory device. In a one-dimensional embodiment, the coding may involve applying a rate 1/2 convolutional code to i least significant bits, i=1, 2, . . . , and mapping the resulting b+i coded bits to one of 2b+i distinct levels in a one-dimensional AM signal set. In embodiments of the invention which utilize multidimensional signal sets, a given set of bits is mapped to a signal in an m-dimensional signal set, with or without coding of the bits, and each of the m dimensions of the selected signal is then stored as a level in a separate cell of the analog memory device. The invention increases the storage capacity of the memory device for a given readout error probability, or alternatively improves the error probability for a given storage capacity. Readout performance may be further improved by using a multiple read-and-sum unit to generate a readout value for a given stored level based on a sum or average of several different readouts of the stored level.
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Citations
44 Claims
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1. A method of storing information bits in an analog memory device, the device including a plurality of analog memory cells, the method comprising the steps of:
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coding at least a portion of a given set of b of the information bits to generate a corresponding set of coded bits including more than b bits, such that the portion of the information bits subject to the coding is transformed into corresponding coded bits in the set of coded bits;
mapping the set of coded bits to one or more corresponding levels; and
storing each of the one or more levels in one of the analog memory cells;
wherein the mapping step is configured to provide at least one of;
(i) an increase in an effective storage capacity of at least a subset of the analog memory cells; and
(ii) a decrease in a readout error probability of at least a subset of the analog memory cells;
relative to an effective storage capacity and a readout error probability associated with storage of unmapped analog levels in the analog memory cells.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An analog memory device for storing a plurality of information bits, comprising:
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a plurality of analog memory cells;
a coder having an input connected to receive the information bits, the coder coding at least a portion of a given set of b of the information bits to generate a corresponding set of coded bits including more than b bits, such that the portion of the information bits subject to the coding is transformed into corresponding coded bits in the set of coded bits; and
a mapper having an input coupled to an output of the coder and receiving the set of coded bits, wherein the mapper is operative to map the set of coded bits to one or more corresponding levels, such that each of the one or more levels can be stored in one of the plurality of analog memory cells;
wherein the mapper is configured to provide at least one of;
(i) an increase in an effective storage capacity of at least a subset of the analog memory cells; and
(ii) a decrease in a readout error probability of at least a subset of the analog memory cells;
relative to an effective storage capacity and a readout error probability associated with storage of unmapped analog levels in the analog memory cells.- View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of storing information bits in an analog memory device, the device including a plurality of analog memory cells, the method comprising the steps of:
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mapping a given set of the information bits to a particular signal in an m-dimensional signal set, the signal including m dimensions; and
storing each of the m dimensions of the signal as a level in a separate one of the analog memory cells. - View Dependent Claims (24, 25, 26, 27, 28)
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29. An analog memory device for storing a plurality of information bits, comprising:
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a plurality of analog memory cells; and
a mapper operative to map a given set of the information bits to a particular signal in an m-dimensional signal set, the signal including m-dimensions, wherein each of the m dimensions of the signal is stored as a level in a separate one of the analog memory cells. - View Dependent Claims (30, 31, 32, 33, 34)
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35. A method of storing information bits in an analog memory device, the device including a plurality of analog memory cells, the method comprising the steps of:
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processing a sequence of symbols, each of the symbols corresponding to a set of the information bits, to generate a sequence of signals selected from an m-dimensional signal set, such that each of the signals includes in dimensions; and
storing each of the m dimensions of a given signal in the sequence of signals as a level in a separate one of the analog memory cells. - View Dependent Claims (36)
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37. An analog memory device for storing a plurality of information bits, comprising:
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a plurality of analog memory cells; and
a coded modulation device for processing a sequence of symbols, each of the symbols corresponding to a set of the information bits, to generate a sequence of signals selected from an m-dimensional signal set, such that each of the signals includes m dimensions, and each of the m dimensions of a given signal in the sequence of signals is stored as a level in a separate one of the analog memory cells. - View Dependent Claims (38)
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39. A method of storing information bits in an analog memory device, the device including a plurality of analog memory cells, the method comprising the steps of:
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coding at least a portion of a given set of b of the information bits to generate a corresponding set of coded bits including more than b bits, such that the portion of the information bits subject to the coding is transformed into corresponding coded bits in the set of coded bits;
mapping a given set of the coded bits to one or more levels;
storing each of the one or more levels in one of the cells of the analog memory device; and
generating a single readout value using results of multiple readouts of a stored level from a given one of the cells wherein the mapping step is configured to provide at least one of;
(i) an increase in an effective storage capacity of at least a subset of the analog memory cells; and
(ii) a decrease in a readout error probability of at least a subset of the analog memory cells;
relative to an effective storage capacity and a readout error probability associated with storage of unmapped analog levels in the analog memory cells.- View Dependent Claims (40, 41)
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42. An analog memory device for storing a plurality of information bits, comprising:
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a plurality of analog memory cells;
a coder operative to code at least a portion of a given set of b of the information bits to generate a corresponding set of coded bits including more than b bits, such that the portion of the information bits subject to the coding is transformed into corresponding coded bits in the set of coded bits;
a mapper operative to map a set of the coded bits to one or more levels, such that each of the one or more levels is stored in one of the plurality of cells; and
a readout unit having an input coupled to an output of a given one of the memory cells, wherein the readout unit is operative to generate a single readout value using results of multiple readouts of a stored level from the given cell;
wherein the mapper is configured to provide at least one of;
(i) an increase in an effective storage capacity of at least a subset of the analog memory cells; and
(ii) a decrease in a readout error probability of at least a subset of the analog memory cells;
relative to an effective storage capacity and a readout error probability associated with storage of unmapped analog levels in the analog memory cells.- View Dependent Claims (43, 44)
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Specification