floorplanning

**Floorplanning Strategy and Methodology** is **high-level spatial organization of major functional blocks on the die — determining block locations, power delivery, and interconnect architecture before detailed design — critical for meeting timing, power, and area targets**. Floorplanning is foundational to physical design, partitioning the chip into major blocks and defining their spatial relationships. Good floorplanning determines whether timing closure is feasible. Critical design decisions: block sizes, locations, power delivery, and memory hierarchy are established. Floorplan Inputs: System architecture defines major blocks — processors, caches, memory controllers, I/O. Block communication bandwidth and latency drive partitioning. Performance requirements guide block interfaces and pipelining. Power budgets and thermal limits constrain block placement. Floorplanning Objectives: minimize wirelength (especially critical interconnect), minimize timing violations (critical path lengths), balance area, and manage power/thermal (hotspot avoidance). Floorplan Generation: Grid-based approach: assigns blocks to grid locations. Slicing structure: recursively partitions area with cuts, creating rectangular regions. Each cut can be vertical or horizontal. Sequence pair: represents floorplan through two permutations of blocks, enabling efficient exploration. Simulated annealing or other search methods find good sequence pairs. Timing-driven floorplanning: places critical blocks close together, reducing interconnect delay on critical paths. Signal flow and block dependencies drive block placement. Power delivery planning: allocates power delivery infrastructure. Supply grid routing determined at floorplanning level. Power grid fragmentation avoided. Voltage drops minimized. Thermal management: high-power blocks avoid clustering (potential hotspots). Heat dissipation paths ensured. Floorplan heterogeneity (non-uniform block sizes) increases complexity but enables specialization. Memory blocks at predictable boundaries simplify routing. Power and clock distribution: separate regions for logic, memory, I/O based on their distinct infrastructure needs. Clock tree synthesis starts from floorplan specification. Hierarchical power delivery: multiple power domains with independent voltage regulation. Floorplan accounts for level shifters and domain crossings. Macros placement: large hardmacros (memory, analog blocks) placed early. Macro timing, blockage, and power characteristics influence placement. Placement legality: adjacent blocks must fit without overlap. Matching interfaces (power/ground, signal) guides block alignment. Congestion analysis: estimated routing congestion from floorplan guides refinement. Congestion hotspots identified and blocks repositioned. ECO margin: floorplan reserves area for late ECO changes. Conservative sizing avoids floorplan breaks from ECO. Tool Support: Commercial tools (Cadence, Synopsys) provide automated floorplanning with user constraints. Manual refinement leverages designer expertise. **Floorplanning strategy determines block locations, power/clock distribution, and critical interconnect, providing foundation for physical design success and meeting timing, power, and area targets.**