characteristics of standard cell

• During the layout design of the cells, the cells are built using a predefined
template that will ensure that all the requirements are met. The template
includes the height of the cell, the placement of wells, N transistors, and P
transistors, and guidelines to follow so that the cell can be flipped vertically
or horizontally and can be placed beside all other cells without creating
errors such as DRC violations.
• Cells are rectangular.
• Cells for specific rows or chip areas are all the same height—a library may
contain multiple sets of cells. For example, different cells will be used for
logic, datapath, and I/O areas.
• Every cell length is rounded up to a multiple of a coarse grid. This grid is
determined by either of the following:
A specific design rule (such as the minimum well width)
A desire to make placement easier and faster (using a coarse grid reduces
the number of possible placement coordinates, thus accelerating the
placement process)
• The power supply lines have a predefined width and position for the entire
library—the width of the supply over the cell length is always consistent.
Re: characteristics of standard cell
some more points to this topic:
1. The pins for a class of cells should lie on same track
2. For analog layout the TAPS will be placed in higher hierarchy of the std cells
3. power EM & sigEM should be taken care in the std cells according to drive strength