Conclusions and Further Work

This experiment has developed an improved Alliance synthesis flow and used it to help in deciding which cells to include in a standard cell library. The improved flow:

The improved flow is targeted at improving the speed of the netlist critical path. This is basically done by setting the cells on the critical path to a high drive strength while keeping the other cells weak. The higher drive strength cells are bigger, so this timing improvement will be at the cost of increased area. The results are compared to the best regular Alliance synthesis from experiment 22.

  0fF wireload
delay in ps
6fF wireload
delay in ps
gate count
standard Alliance flow, BOOG then LOON 2373 2788 1541
new flow 2142 2441 1758
difference -9.7% -12.4% +14.1%

With this new flow, and starting from a very basic library, cells are added in stages and the timing improvement monitored. At the end of this phase, the library has 188 cells. Cells are then removed until a maximum acceptable loss of performance has been reached. This library has 92 cells.

Further work which will be presented later includes: