From Floorplanning to Routing Closure

Physical design turns logical circuit intent into a geometric silicon layout that can satisfy timing, routing, power, and manufacturing requirements. The process begins with implementation planning, where the design is organized into physical regions and prepared for downstream optimization. A top-level netlist provides the logical connectivity, while physical constraints define die size, block area, I/O organization, power resources, and early implementation limits. Floorplanning establishes the first major physical structure of the chip. It defines die dimensions, allocates area for soft blocks, places or reserves space for macros, organizes I/O locations, and prepares power structures. Block placement, module organization, utilization control, and routing-resource planning are handled at this stage to reduce downstream risk. Flightlines and connectivity views help reveal communication intensity between blocks, allowing highly connected regions to be placed closer together and reducing unnecessary wire length. Placement converts the floorplan into legal cell locations. Sites and rows define where cells may be placed, while library information determines the legal row type for each cell. Placement decisions influence congestion, timing paths, routing demand, and overall layout efficiency. Poor placement can increase wire delay, create routing blockages, and make timing closure harder, even when the logical design is functionally correct. Timing closure connects physical implementation quality with circuit performance. Signal paths must satisfy timing limits after accounting for gate delay, wire delay, clock distribution, buffering, and routing effects. Clocking decisions strongly affect this process because clock arrival time, skew, and uncertainty determine how much margin remains for data paths. Optimization may involve placement refinement, buffering, logic restructuring, clock adjustment, or routing changes. Routing creates the actual wire geometries that connect cells, macros, I/O ports, power structures, and clock networks. Routing quality affects delay, noise, signal integrity, congestion, and manufacturability. Physical verification then checks whether the final layout follows manufacturing rules and still matches the intended circuit. A well-controlled flow from floorplanning to routing improves convergence, reduces late-stage rework, and supports reliable silicon implementation. Catalogue: Implementation and Verification Flow Implementation Flow Overview Basic Flow: Implementation (I) Basic Flow: Implementation (II) Floorplanning and Placement Floorplanning and Placement Impact on RTL Example: Placement Understanding Timing Closure Timing Closure Process Clocking Impact on Timing Closure Routing Impact on Timing Closure Physical Verification and Timing Closure Timing Closure Impact on RTL Placement Sites and Rows Floorplanning Tasks and Checks Floorplanning Fundamentals Block Placement in Floorplanning Floorplanning Inputs and Outputs Example: Floorplanning I Example: Floorplanning II Initial Floorplanning Setup Module Placement Strategies Using Flightlines for Floorplanning