o Gather Inputs:
o
Gate Count: Number of standard logic
gates from synthesis (excluding memories/macros).
o
Memory/Macro Area: Total area required
for all hard macros, RAMs, ROMs, IP blocks (obtained from their datasheets or
abstracts).
o
IO Count: Number of Input/Output
pads/bumps required.
o
Technology Information: Gate density
(gates/mm²) for the target standard cell library, standard cell height,
required IO pad dimensions/pitch.
o
Target Utilization: The desired
percentage of the core area that will be occupied by standard cells and macros
after placement.
o
Overhead Estimation: Percentage allowance
for Clock Tree Synthesis (CTS) buffers/inverters, routing overhead, ECO margin,
physical cell placement (decap, filler), etc. (e.g., add 10-20% to gate count).
o Calculate
Core Area:
o
Standard Cell Area: (Gate Count + Gate
Count * Overhead%) / Gate Density
o
Total Core Logic Area: Standard Cell Area
+ Memory/Macro Area
o
Estimated Core Area: Total Core Logic
Area / Target Utilization
o Calculate
IO Area / Peripheral Area: Determine the area required for the IO pads
based on their count and dimensions/pitch. This depends on whether the design
is pad-limited or core-limited.
o
Pad-Limited: The number and size of IO
pads dictate the minimum perimeter and thus the minimum die size. The core must
fit within this boundary.
o
Core-Limited: The calculated core area
dictates the die size, and the IO pads must fit around this core.
o Estimate
Die Size: Combine the core area and peripheral/IO area.
o
For a core-limited design, the die area is
roughly the core area plus the surrounding IO area/channels.
o
For a pad-limited design, calculate the minimum
dimensions required by the pads and ensure the estimated core area fits inside.
o Consider
Aspect Ratio: Decide on the desired Height/Width ratio for the die (often
close to 1.0 for square, but can vary based on packaging or system
constraints). Calculate the die dimensions (Height, Width) based on the
estimated Die Area and Aspect Ratio:
1. Die
Area = Width * Height
2. Aspect
Ratio (AR) = Height / Width
3. Height
= sqrt(Die Area * AR)
4. Width = sqrt(Die Area / AR)
o Floorplan
Initialization: https://openroad.readthedocs.io/en/latest/main/src/ifp/README.html
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