Cell design
One or more techniques or systems for designing a cell are provided. The cell generally includes one or more transistors, such as a pass gate transistor, a pull up transistor, or a pull down transistor, respectively associated one or more gate to gate distances. In some embodiments, a second gate to gate distance is selected based on a first gate to gate distance. For example, the first gate to gate distance and the second gate to gate distance are associated with a first transistor. In another example, the first gate to gate distance is associated with a first transistor and the second gate to gate distance is associated with a second transistor. In this manner, a cell design is provided to improve a static noise margin (SNM) or a write margin (WM) for the cell, for example.
1. A transistor array of a cell, comprising:
a first transistor comprising:
a first gate, and
a first region having a first length, the first region comprising at least one of a first source or a first drain; and
a second transistor comprising:
a second gate, and
a second region abutting the first region, the second region having a second length different than the first length, the second region comprising at least one of a second source or a second drain, wherein:
a ratio of the first length to the second length is a function of at least one of a desired alpha ratio for the transistor array or a desired beta ratio for the transistor array.
2. The transistor array of the cell of claim 1 , the first region having a first width and the second region having a second width different than the first width.
3. The transistor array of the cell of claim 2 , the first transistor comprising a pull up transistor and the second transistor comprising a pass gate transistor and wherein the desired alpha ratio is equal to a first ratio between the first width and the first length divided by a second ratio between the second width and the second length.
4. The transistor array of the cell of claim 2 , the first transistor comprising a pull down transistor and the second transistor comprising a pass gate transistor and wherein the desired beta ratio is equal to a first ratio between the first width and the first length divided by a second ratio between the second width and the second length.
5. The transistor array of the cell of claim 1 , the first transistor comprising a third region having a third length substantially equal to the first length, the third region different than the first region and comprising at least one of the first source or the first drain.
6. The transistor array of the cell of claim 5 , the second transistor comprising a fourth region having a fourth length substantially equal to the second length, the fourth region different than the second region and comprising at least one of the second source or the second drain.
7. The transistor array of the cell of claim 5 , the first region having a first width and the third region having a third width substantially equal to the first width.
8. A transistor array of a cell, comprising:
a first transistor comprising:
a first region having a first width, the first region comprising at least one of
a first source or a first drain;
a second transistor abutting the first transistor and comprising:
a second region having a second width different than the first width, the second region comprising at least one of a second source or a second drain; and
a third transistor abutting the second transistor and comprising:
a third region different than the second region and having the second width, the third region comprising at least one of a third source or a third drain.
9. The transistor array of the cell of claim 8 , wherein:
the first region has a first length and the second region has a second length different than the first length.
10. The transistor array of the cell of claim 8 , wherein:
the first region has a first length and the third region has a second length different than the first length.
11. The transistor array of the cell of claim 8 , wherein:
the second region and the third region have a same length.
12. The transistor array of the cell of claim 8 , wherein:
the first region has a first length,
the second region has a second length different than the first length; and
the third region has the second length.
13. The transistor array of the cell of claim 12 , wherein the first width, the first length, the second width, and the second length are selected as a function of at least one of a desired alpha ratio of the transistor array or a desired beta ratio of the transistor array.
14. The transistor array of the cell of claim 8 , comprising:
a fourth transistor abutting the third transistor and comprising:
a fourth region having the first width, the fourth region comprising at least one of a fourth source or a fourth drain.
15. The transistor array of the cell of claim 14 , wherein:
the first region and the fourth region have a first length, and
the second region and the third region have a second length different than the first length.
16. The transistor array of the cell of claim 8 , comprising:
a contact between the second transistor and the third transistor.
17. The transistor array of the cell of claim 8 , wherein a ratio of the first width to the second width is a function of at least one of a desired alpha ratio for the transistor array or a desired beta ratio for the transistor array.
18. A transistor array of a cell, comprising:
a first transistor comprising a first region having a first set of dimensions, the first region comprising at least one of a first source or a first drain;
a second transistor comprising:
a second region abutting the first region and having a second set of dimensions, the second set of dimensions differing from the first set of dimensions in at least one of width or length; and
a third region having the second set of dimensions, the second region comprising at least one of a second source or a second drain and the third region comprising at least one of the second source or the second drain; and
a third transistor comprising a fourth region abutting the third region and having the second set of dimensions, the fourth region comprising at least one of a third source or a third drain.
19. The transistor array of the cell of claim 18 , comprising:
a fourth transistor comprising a fifth region abutting the fourth region and having the first set of dimensions, the fifth region comprising at least one of a fourth source or a fourth drain.
20. The transistor array of the cell of claim 18 , wherein at least some of the first set of dimensions or the second set of dimensions are selected as a function of at least one of a desired alpha ratio of the transistor array or a desired beta ratio of the transistor array.