Multi-level flash storage device with minimal read latency
First Claim
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1. A memory system, comprising:
- a flash memory array having a plurality of memory cells that store data therein, each of the plurality of memory cells being organized into pages on different media of the flash memory array; and
a controller configured to read a page of a selected one of the different media by applying a single threshold voltage to the flash memory array,wherein a combination of at least two of the plurality of memory cells is assigned to one of multiple possible states to store the data,wherein the controller reads the page of the selected one of the different media with the single threshold voltage that corresponds to one of multiple possible threshold voltages associated with the multiple possible states, andwherein the controller selects the single threshold voltage from a table that contains a mapping of the multiple threshold voltages to the pages of the different media such that the single threshold voltage for reading the page varies based on which of the different media is the selected one of the different media.
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Abstract
A memory system, non-volatile solid-state memory, and a method of efficiently reading data from a flash memory array are disclosed. The disclosed memory system includes a flash memory array having a plurality of memory cells that store data therein, each of the plurality of memory cells being configured to store at least two bits per cell and being organized into pages, and a controller configured to read any bit of data from a page of the flash memory array by applying a single threshold voltage to the flash memory array. Reading data from the flash memory array with a single threshold greatly decreases the latency associated with the read operation.
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20 Claims
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1. A memory system, comprising:
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a flash memory array having a plurality of memory cells that store data therein, each of the plurality of memory cells being organized into pages on different media of the flash memory array; and a controller configured to read a page of a selected one of the different media by applying a single threshold voltage to the flash memory array, wherein a combination of at least two of the plurality of memory cells is assigned to one of multiple possible states to store the data, wherein the controller reads the page of the selected one of the different media with the single threshold voltage that corresponds to one of multiple possible threshold voltages associated with the multiple possible states, and wherein the controller selects the single threshold voltage from a table that contains a mapping of the multiple threshold voltages to the pages of the different media such that the single threshold voltage for reading the page varies based on which of the different media is the selected one of the different media. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A non-volatile solid-state memory, comprising:
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a plurality of memory cells that store data therein, each of the plurality of memory cells being organized into pages on different media of the non-volatile solid-state memory, wherein each page of a selected one of the different media is readable with a single threshold value, wherein a combination of at least two of the plurality of memory cells is assigned to one of multiple possible states to store the data, wherein each page is readable with the single threshold value that corresponds to one of multiple possible threshold values associated with the multiple possible states, wherein the multiple possible threshold values are mapped to the pages of the different media in a table such that the single threshold value for reading each page varies based on which of the different media is the selected one of the different media, and wherein each of the multiple possible threshold values are represented in the table by at least two bits. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method, comprising:
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receiving a request to read data from a page of a selected one of different media of a flash memory array, the flash memory array including a plurality of memory cells; determining a single voltage threshold to apply in connection with the request; applying the single voltage threshold to a word line of the selected one of the different media in the flash memory array; and reading an entirety of the page using the single applied voltage threshold, wherein a combination of at least two of the plurality of memory cells is assigned to one of multiple possible states to store the data, wherein the reading includes reading the page with the single voltage threshold that corresponds to one of multiple possible voltage thresholds associated with the multiple possible states, and wherein the determining the single voltage threshold includes selecting the single voltage threshold from a table that contains a mapping of the multiple possible voltage thresholds to the pages of the different media such that the single voltage threshold for reading the page varies based on which of the different media is the selected one of the different media.
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Specification