Area and utilization
Each summary describes a real run. Say whether the metric lands over or under the number asked, and the measured value is revealed against it. Keys o and u answer, h shows a hint, and Enter moves on. Guessing gets half right, so the score only means something above that. Progress is stored in this browser.
All 6 summaries in this family, with their numbers
-
gcd on Nangate45, 45 nanometre: Is the final cell area over 900 square micrometres?945 square micrometres, so over
Chasing 0.30 nanoseconds cost 32 percent more area and never met the constraint. This is the shape of an over-constrained block: the area climbs, the slack barely moves, and the run still fails. The area is the evidence that the target, not the implementation, is wrong.
-
gcd, the same source on sky130 high density, 130 nanometre: Is the final cell area over 3000 square micrometres?5400 square micrometres, so over
The same source occupies 7.5 times the area at 130 nanometres that it does at 45, and that is not purely the node: synthesis produced a different netlist for this library, 222 instances against 521. Both effects push the same way, and neither can be separated from the other by looking at the total. A figure quoted without its process and its netlist says almost nothing.
-
aes against gcd, both on Nangate45 on Nangate45, 45 nanometre: Is the area per cell more than 50 percent larger on the big design?10 percent larger, so under
1.26 square micrometres a cell against 1.14, which is 10 percent. Cell area is a property of the library and the mix of cells, not of the size of the design, so it stays put as a design grows. Wire length is the thing that grows superlinearly, which is why interconnect, not cells, is what limits large blocks.
-
gcd, the same source again on ASAP7, a 7 nanometre predictive kit, on a 0.77 volt supply: Is the cell area over 100 square micrometres?46 square micrometres, so under
46 square micrometres, against 716 at 45 nanometres and 5400 at 130. The whole block fits in a square about seven micrometres on a side. Scaling is the reason a design that was a chip in one generation is a corner of a chip in the next, and why area comparisons across nodes are close to meaningless without both numbers.
-
aes on sky130 high density, 130 nanometre: Is the cell area over 100000 square micrometres?126974 square micrometres, so over
126974 square micrometres, 6.4 times the Nangate45 figure, close to the 7.5 the small block showed. The ratio between two processes is stable enough across designs to estimate with, which is what makes these comparisons worth learning rather than looking up each time.
-
gcd, run three times on Nangate45, 45 nanometre: Do the three runs differ in final cell area by more than 5 percent?2 percent, largest against smallest, so under
723, 716 and 709 square micrometres, a spread of two percent, and the loosest run is the largest because repair had longer wires to drive. Utilization sets how much empty space surrounds the cells, not how many there are. Within the normal range the knob does far less than people expect, which is worth knowing before spending a day sweeping it.