Power Planning

What is Power Planning????

         Power planning is a step which typically is done with floorplanning in which power grid network is created to distribute power to each part of the design equally.
•Power planning can be done manually as well as automatically through the tool.
•Deal with Power Distribution Network

Three levels of Power Distribution

Rings

Carries VDD and VSS around the chip

Stripes

Carries VDD and VSS from Rings across the chip

Rails

Connect VDD and VSS to the standard cell VDD and VSS.

ØEM(electro migration) and IR(V=IR voltage drop)

ØThis step involves placement of:

•Core power ring

•Vertical and Horizontal power straps in the core

•Standard cells power hook up

•Block power hook up

•IO power hook up

ØPower dissipation figure is first estimated through a tool or through calculations

Based on this, the power ring width, power strap width, no. of vertical and horizontal straps etc. are calculated.

ØThe Power and Ground vertical and horizontal straps are also created to distributed power inside the core area i.e. to macros and standard cells. Finally the macro and standard cells pin connections are done to the straps and power and ground rails respectively.