flip-flops can cut dynamic power by roughly 23.7% and total power by about 8.6% due to shorter net length, and global clock buffers can drop by around 37.8%.
- Lower clock skew in sequential gates, since the clock paths are balanced internally within a single multibit cell.
- Smaller overall SoC area, because the total number of clock buffers falls, which also reduces congestion.
- Better timing numbers, due to shared logic (in clock gating or set-reset logic) and the optimized multibit circuit and layout from the library team.
Cons:
- IR-drop issues.
- Electromigration violations.
- LEC difficulty - since logical equivalence checking compares names, an SVF file is needed to map the multibit flops back to their single-bit equivalents.
KEY Multibit flops cut area, clock-tree length, buffers, power and skew - but raise IR-drop, EM and LEC challenges.
TCL - Print Error Lines from a File
Open the file in read mode with the open command, then loop using gets to read it line by line.
Inside the loop, use regexp to test whether the line matches the Error pattern; if it matches, print the line, otherwise continue to the next line.
KEY Open the file, read line by line with gets, and use regexp to print only lines matching 'Error'.
Inputs to a .lib File
- The input transition.
- The output load.
KEY A .lib takes input transition and output load as its inputs.