Eight transistor SRAM cell with improved stability requiring only one word line
First Claim
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1. A static random access memory comprising in combination:
- a plurality of bi-stable memory cells arranged in rows and columns;
each of said plurality of memory cells includes a first pull-up transistor and a first pull-down transistor coupled in series between a supply voltage and common and cross coupled with a second pull-transistor and a second pull-down transistor connected in series between said supply voltage and common, and with a first node between said first pull-up transistor and said second pull-down transistor and a second node between said second pull-up transistor and said second pull-down transistor;
cells in a column each connected via a pair of write access devices to a pair of write bit lines for writing data into said cell;
said cells in a column each connected via a read access device to a read bit line, separate from said pair of write bit lines, for reading data from said cell; and
cells in a row each connected via a word line access device to a single word line;
whereby activation to respective predetermined states of said word line and said pair of write bit lines writes data to said cell and activation of said word line and said read bit line reads data from said cell.
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Abstract
An SRAM cell that is accessed by a single word line and separate access transistors for read and write operations. A pair of write bit line transfer devices provide respectively access to the right and left sides of cross coupled pull-up, pull-down transistor pairs for a write operation, and a single read bit line transistor in series with the word line transistor, when selected, reads the content of the cell.
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Citations
17 Claims
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1. A static random access memory comprising in combination:
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a plurality of bi-stable memory cells arranged in rows and columns;
each of said plurality of memory cells includes a first pull-up transistor and a first pull-down transistor coupled in series between a supply voltage and common and cross coupled with a second pull-transistor and a second pull-down transistor connected in series between said supply voltage and common, and with a first node between said first pull-up transistor and said second pull-down transistor and a second node between said second pull-up transistor and said second pull-down transistor;
cells in a column each connected via a pair of write access devices to a pair of write bit lines for writing data into said cell;
said cells in a column each connected via a read access device to a read bit line, separate from said pair of write bit lines, for reading data from said cell; and
cells in a row each connected via a word line access device to a single word line;
whereby activation to respective predetermined states of said word line and said pair of write bit lines writes data to said cell and activation of said word line and said read bit line reads data from said cell. - View Dependent Claims (3, 5, 6, 7, 8)
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2. (canceled)
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4. (canceled)
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9-10. -10. (canceled)
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11. A static random access memory comprising in combination:
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a plurality of bi-stable memory means arranged in rows and columns;
each of said plurality of bi-stable memory means includes a first pull-up transistor and a first pull-down transistor coupled in series between a supply voltage and common and cross coupled with a second pull-transistor and a second pull-down transistor connected in series between said supply voltage and common, and with a first node between said first pull-up transistor and said second pull-down transistor and a second node between said second pull-up transistor and said second pull-down transistor;
said memory means in a column each coupled to write access means for writing data into said cell;
said memory means in a column each connected a read access means separate from write access for reading data from said cell; and
said memory means in a row each coupled to a word line access;
whereby activation to respective predetermined states of said word line means and said write access means writes data to said cell and activation of said word line means and said read access means reads data from said cell. - View Dependent Claims (13, 14, 16, 17)
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12. (canceled)
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15. (canceled)
Specification