Parameters of Floorplanning

 In the floorplanning, while doing floorplan, we have to keep in mind some parameters. Today, we are going to discuss those.

Aspect Ratios

Aspect Ratio is the ratio of width to height of the core. It is also defining the ratio of horizontal to vertical routing resources.

Core utilization

Core utilization is the percentage of the core area of the block is used by standard cell placement and Macros. Ideally, it would like to achieve 100% utilization, but in practice, the range is 80-90%

It is recommended that starting netlist utilization netlist should not exceed 70-75% to allow for logic optimization.

Blockages

The blockage is the region where the placement of cell is restricted. There are Placement blockage and Routing blockage.

Placement Blockage:

Soft Blockage: The region where the placement of standard cells is restricted but the placement of buffers and inverters are allowed in order to meet the timing optimization.   

Hard Blockage: The region where the placement of standard cells is restricted and nothing is allowed inside that region.

Routing blockage:

Signal Blockage: The region where any kind of signal (data/clock) is restricted. While do so, we have to specify for metal layer signal we have to block.

Power Blockage: The region where power rails (VDD/VSS) is restricted. While do so, we have to specify for metal layer signal we have to block.

 

Keepout Margins (Halo)

Keepout margin is the region around the macros is restricted for placing any kind of cells in order to avoid overlapping.

It is kind of blockage which is moved with the cell or macro.  

 

Core-limited Design

A core limited design is when the die size is determined by the logic of the design i.e. the utilization of cell and macros.

Pad-limited Design

A pad limited design is when the die size is determined by the number of pads rather by the size of the core

 

At this note of discussion, we wrapped up this topic and we will meet soon with a new topic of Floorplan. Thank you. Have a nice day!!!