Methods and systems for read-only memory
AssigneeTexas Instruments Incorporated
InventorsDavid B. Scott, Radu Avramescu
Life of this patent
Estimating the term…
Abstract
One embodiment of the present invention relates to a read only memory (ROM) that includes a memory cell pair. The memory cell pair includes a first memory cell and a second memory cell that share a common drain that is associated with the memory cell pair. The memory cell also includes a bitline configured to provide data from the first and second memory cells, wherein the bitline is electrically isolated from the common drain. Other methods and systems are also disclosed.
Claims17
A read only memory including a memory cell pair with first and second memory cells that share a common drain, the memory cell pair comprising:
- a first memory cell comprising:
- a first source formed in a semiconductor substrate, the first source and common drain disposed along a linear line segment and separated from one another by a first region of semiconductor substrate;
- and
- a first wordline disposed over the first region of semiconductor substrate;
- and
- a second memory cell comprising:
- a second source formed in the semiconductor substrate, the second source disposed along the linear line segment and separated from the common drain by a second region of semiconductor substrate;
- a second wordline disposed over the second region of semiconductor substrate;
- and
- a bitline configured to read data from the first and second memory cells, wherein the bitline is electrically isolated from the common drain.
A read only memory comprising a memory cell pair that comprises:
- a first memory cell having a first source and a common drain disposed along a linear line segment, wherein the first source and the common drain are separated by a distance related to a first word line of the read only memory;
- a second memory cell having a second source disposed along the linear line segment, where the second memory cell shares the common drain with the first memory cell and has a second wordline associated therewith;
- and
- a bitline configured to read data from the first and second memory cells as a function of the first and second wordlines, respectively, wherein the bitline is electrically isolated from the common drain.
A read only memory, comprising:
- a number of memory cell pairs that are associated with two or more wordlines, wherein a memory cell pair comprises two memory cells that share a common drain coupled to a bitline of the memory cell pair;
- the two memory cells being respectively associated with two of the wordlines, and
- at least two contacts configured to couple the common drains of adjacent memory cell pairs to their respective bitlines, wherein the at least two contacts have different respective offsets as measured from a first of the two wordlines.
A read only memory comprising a number of memory cells arranged in a series of rows and columns, comprising:
- a first memory cell pair along a first column, the first memory cell pair comprising:
- first and second memory cells that share a first common drain, wherein a first bitline contact couples the first common drain to a first bitline associated with the first memory cell pair, the first bitline contact arranged between first and second wordlines respectively associated with the first and second memory cells and offset by a first distance from the first wordline;
- and
- a second memory cell pair along a second column, the second memory cell pair comprising:
- third and fourth memory cells that share a second common drain, wherein a second bitline contact couples the second common drain to a second bitline associated with the second memory cell pair, the second bitline contact arranged between the first and second wordlines and offset by a second distance from the first wordline, the second distance being different than the first distance.
Dependencies are inferred from the claim text.