Hi Everyone,
In the previous post, i have discussed on Floorplan. In the current session, i will try to explain the importance of Power plan and why it is needed.
Each and every circuitry in the IC needs power. So, the Power planning must be done in order to achieve the ultimate goal of Power dissipation reduction. Now, here you may get the doubt, like How can we reduce the power dissipation by mere Power Planning? The answer is, in an IC we have few power hungry circuits like clock which eat up most of the power, which has to be placed propeerly so as to reduce the amount of power dissipated in transmitting the power to it and the other way of Power dissipation is through IR drops.
We need to design a proper mesh so as to deliver Power to each and every circuit with minimal loss. As we know a long wire will have resistance which is proportional to its length. This can be understood with mere formula for resistance as shown below
R=k*L/W
where k=the resistivity constant(sorry could find rho letter here)
L=length of the wire
W=width of the wire
So from the equation we can say that if we have long wire, it means it has high resistance, if we dont increase the width. The point is, Power has to be transmitted through such wires to reach the corner most point of the IC. It means, if we don't select the proper mesh structure, it is sure that we end up losing lots of power as heat and hence spoil the IC. So we need to design a effective Power Mesh and hence need to do Power Planning.
There are other factors like Electro Migrations(discussed in my very first blog), which should be taken care of while doing the Power Planning.
There are three techniques in designing a Power mesh. they are.
1)2-D layer Design
2)1-D layer design
3)Row based design
In 2-D layer design we use one layer for Vdd and one for ground. In 1-D layer design we use only one layer for both, in the sense the system or block is partitioned and routed accordingly. Row based design is generally used for standard cells which are placed in row fashion.
The resource for all the above explanation is from the World's best search engine also called Google. Please search difficult words in http://www.google.com and know more about them.
Thank You
In the previous post, i have discussed on Floorplan. In the current session, i will try to explain the importance of Power plan and why it is needed.
Each and every circuitry in the IC needs power. So, the Power planning must be done in order to achieve the ultimate goal of Power dissipation reduction. Now, here you may get the doubt, like How can we reduce the power dissipation by mere Power Planning? The answer is, in an IC we have few power hungry circuits like clock which eat up most of the power, which has to be placed propeerly so as to reduce the amount of power dissipated in transmitting the power to it and the other way of Power dissipation is through IR drops.
We need to design a proper mesh so as to deliver Power to each and every circuit with minimal loss. As we know a long wire will have resistance which is proportional to its length. This can be understood with mere formula for resistance as shown below
R=k*L/W
where k=the resistivity constant(sorry could find rho letter here)
L=length of the wire
W=width of the wire
So from the equation we can say that if we have long wire, it means it has high resistance, if we dont increase the width. The point is, Power has to be transmitted through such wires to reach the corner most point of the IC. It means, if we don't select the proper mesh structure, it is sure that we end up losing lots of power as heat and hence spoil the IC. So we need to design a effective Power Mesh and hence need to do Power Planning.
There are other factors like Electro Migrations(discussed in my very first blog), which should be taken care of while doing the Power Planning.
There are three techniques in designing a Power mesh. they are.
1)2-D layer Design
2)1-D layer design
3)Row based design
In 2-D layer design we use one layer for Vdd and one for ground. In 1-D layer design we use only one layer for both, in the sense the system or block is partitioned and routed accordingly. Row based design is generally used for standard cells which are placed in row fashion.
The resource for all the above explanation is from the World's best search engine also called Google. Please search difficult words in http://www.google.com and know more about them.
Thank You
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