1.5. Power Analysis in Modular Design Flows
A common design practice is to create modular or hierarchical designs in which you develop each design entity separately, and then instantiate these modules in a higher-level entity to form a complete design. You can perform simulation on a complete design or on each module for verification. The Power Analyzer supports modular design flows when reading the signal activities from simulation files. The following figure shows an example of a modular design flow.
- When you apply multiple .vcd files to the same design entity, the Power Analyzer calculates the signal activity as the equal-weight arithmetic average of each .vcd.
- When you apply multiple simulation files to design entities at different levels in the design hierarchy, the signal activity in the power analysis derives from the simulation file that applies to the most specific design entity.
The following figure shows an example of a hierarchical design:
The top-level module of the design, called Top, consists of three 8b/10b decoders, followed by a mux. The software encodes the output of the mux to produce the final output of the top-level module. An error-handling module handles any 8b/10b decoding errors. The Top module contains the top-level entity of the design and any logic not defined as part of another module. The design file for the top-level module can be a wrapper for the hierarchical entities or can contain its own logic.
The following usage scenarios show common ways that you can simulate the design and import the .vcd into the Power Analyzer: