Power Planning

Let , Power = 100mW   Voltage = 1v

Recall the formula

P= VI  => I = P/V

= 100/1

= 100mA

Since we assume that there are four pads of Vdd and vss

Then each pad can take a 25 mA of current

Again we have the technology LEF file

In that for a particular metal (M8) the current carry strength will be given

For example M8 - 1µ width of wire - the current carrying strength is 10mA

Now for 2.5µ = 2.5mA

Spacing =25 µ

If the core width of floorplan is 1mm

No of vertical straps =core width/ spacing

1mm/ 25 µ = 40 straps

Width of the each strap = width of the power ring / no of vertical straps

= 2.5/ 40 =0.625µ

Spacing =25 µ

If the core height of floorplan is 1mm

No of horizontal straps =core height / spacing

1mm/ 25 µ = 40 straps

Width of the each strap =height of the power ring / no of horizontal straps

= 2.5/ 40 =0.625µ