Starting Synthesis with x1 Gates

gate count               1456
number of cells           666
number of library cells    70
number of used cells       30
max fanin                  17
max input capacitance     211
max internal fanout        34
critical path  0fF       2415
critical path  6fF       3056

The effect of synthesising with BOOG to x1 drive strength cells is to make these cells effectively available, since previously LOON would never downsize a cell from an x2 drive strength.

The cells affected are the AND and OR gates, an2,an3,an4 and or2,or3,or4 and the 2-NAND gate nd2v0x2. The number of x2 drive strength cells switched to x1 drive strength in the final netlist is:

 1/5   an2v0x1
33/81  iv1v0x1
 1/3   nd2v0x1
 2/2   or2v0x1
 1/1   or3v0x1
 1/1   or4v0x1

So six new cells are used which otherwise would not be chosen by LOON. The critical path improves by 0.2% at the cost of an area increase of 1.6%.

The next experiment is to synthesise with BOOG to x05 cell drive strengths and use LOON to buffer up where needed to improve the critical path.