Standard Cell Library
Standard cells are designed based on power, performance and
area. Cell architecture is deciding by cell height which is based on pitch. The
track, pitch, ? ratio, and possible PMOS and NMOS width constant for particular
Pitch is the distance between two tracks.
width) + Via overhead +Metal-to-metal spacing
Standard Height = Pitch * (M-1)
represents the number of tracks.
? is the ration between the PMOS width and NMOS width.
Standard cell library contains cells of threshold devices (eg- Standard Vt and
Hight Vt) and different drive strength (multiple fingering).
Different category of
Cells in universal Library
Basic gated (AND, OR, NOT, NAND, NOR, XOR, XNOR)
Half Adder and Full Adder
Metal Ecoable cells
Flops (D Flip flop and Scan-able flop with
Spare Cells (Fillers, Tap cells, Decaps.. etc)
Boolean functional cells
Power management cells (Isolation cell, Level
Shifter, Power gate/switch)
cells are used to provide substrate connection and avoid latch-up. The cells
used to connect n-well to VDD and p-substrate top VSS.
filler cells which are converted to attain any functionality are called metal
ECO cells. The size of these cells is more as compared to normal cells of same
cells are used to provide power rail continuity. This cells also contain p
substrate and n-well.
Cells (Decap cells)
used in design between power and ground rails. These cells behaves like a
battery when drops present in power rail and maintain the voltage across rails.
These cells aids IR drop issue and removes glitches in power.
End cap cells
added near the end of rows to terminate the rows properly.
are 2 type of TIE cell:- TIE High (give output VDD) & TIE Low (give output
In design some cell input require a
logic 0 or logic 1 value. Rather than providing connection to VDD/VSS rails,
you connect them to TIE cells. Tie cells are used to avoid direct connection to
power rails to protect cell from damage.