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Other Inverting Gates with 4 Inputs - aoi211, aoi31, oai211, oai31

The netlist also shows gate combinations like the following:

ex14_1 example

   
gate count               1378
number of cells           551
number of library cells   103
number of used cells       39
max fanin                  17
max input capacitance     189
max internal fanout        34
critical path  0fF       2324
critical path  6fF       2893
   aoi211 aoi211 symbol
   aoi31 aoi31 symbol
   oai211 oai211 symbol
   oai31 oai31 symbol

The 3-NAND into a 2-AND is very similar to a 3-AND into 2-NOR, which is an inverting complex gate aoi31. We can add 4 such gate types, shown on the right. Each has the usual three drive strengths of x05, x1 and x2, so the total number of library cells increases from 91 up to 103.

Actually, the oai211v0x2 timing is only estimated, since the cell hasn't been drawn yet. The function isn't chosen by BOOG, so there is no impact on the multiplier timing.
The full cell list now is: 

aoi21          x05 x1 x2            3
aoi22          x05 x1 x2            6
aoi211         x05 x1 x2            9
aoi31          x05 x1 x2           12
an2,an3,an4 .  x05 x1 x2           21
cgi2           x05 x1 x2           24
iv1     x05 x1 x2 x3 x4 x6 x8 x12  32
mxi2           x05 x1 x2           35
nd2,nd3,nd4    x05 x1 x2           44
nd2a           x05 x1 x2           47
nd2ab          x05 x1 x2           50
nr2,nr3.nr4    x05 x1 x2           59
nr2a           x05 x1 x2           62
oai21          x05 x1 x2           65
oai22          x05 x1 x2           68
oai211         x05 x1 x2           71
oai31          x05 x1 x2           74
or2.or3.or4    x05 x1 x2           83
or3v3,or4v3           x2           85
xaoi21,xaon21  x05 x1 x2           91
xooi21,xoon21  x05 x1 x2           97
xnr2,xor2      x05 x1 x2          103

BOOG chooses one oai31 and two aoi31 cells which reduces the cell count from 553 to 551.
The circuit speed improves from 2908 to 2893, or 0.5%.

Table of synthesis results  
  critical path (ps) gate count cell count porosity library cells used cells
synthesis 1 4279 1561 923 43%   9  8 basic inverters, NAND & NOR gates
synthesis 2 4236 1472 792 45%  15 12 AND & OR gates
synthesis 3 4157 1357 696 46%  19 16 AOI & OAI gates, 2/1 and 2/2
synthesis 4 4157 1357 696 46%  20 16 mxi2 2-way inverting mux
synthesis 5 3983 1343 668 48%  21 16 cgi2 carry generator inverting
synthesis 6 3948 1352 668 48%  28 18 inverters with multiple drive strengths
synthesis 7 3061 1433 666 51%  70 27 x2 drive strengths for all functions
synthesis 8 3056 1456 666 52%  70 30 BOOG with x1 drive strengths
synthesis 9 2960 1476 666 53%  70 32 BOOG with x05 drive strengths
synthesis 10 2963 1480 666 53%  76 34 nd2a and nr2a cells
synthesis 11 2963 1480 666 53%  79 34 nd2ab type of 2-OR
CyHP library 3778 1539 832 46%  18 17 Minimum size library
synthesis 12 2908 1362 553 54%  91 38 AND/OR into XOR/XNOR
synthesis 13 2893 1378 551 55% 103 39 aoi211, aoi31, oai211 & oai31
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