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gate count 1611 number of cells 540 number of library cells 167 number of used cells 49 max fanin 17 max input capacitance 199 max internal fanout 34 critical path 0fF 2149 critical path 6fF 2523 |
Now an x6 drive strength is added for those functions where its size is not too big:
an2v0x6 an3v0x6 aoi21v0x6 nd2v0x6 nd2av0x6 nd2abv0x6 nd3v0x6 nr2v0x6 nr2av0x6 oai21v0x6 or2v0x6 or3v0x6 |
a total of 12 new cells.
Compared to the previous experiment, where only inverters had a drive strength above x4, there is a 1.7% speed improvement at the cost of a 2.5% area increase. The x6, x4 and x3 drive strength usage is:
x3 x4 x6
an2 0 0 2
aoi22 1 0 -
cgi2 15 - -
iv1 1 12 10
nd2a 0 2 0
nr2a 0 1 0
nr2 0 0 1
oai21 9 10 9
xaon21 2 - -
xnr2 1 - -
xoon21 3 - -
xor2 14 1 -
TOTAL 46 26 22 |
17% of the cells are larger than an x2 drive strength. As before, the bulk of the x6 usage is with the oai21v0x6 cells.
The critical path below shows an xooi21v0x05
weak drive strength cell with a delay of 161ps.
Its presence shows that there is another parallel
critical path, slightly faster, also driven by
gate no. 6, the oai21v0x6.
If the xooi21v0x05 is buffered up, it slows down
the oai21v0x6 which in turn makes the second critical
path slower than this one (by 2ps).
The parallel critical path is the one with the x6
drive strength oai21 cells.
x 1 17 199
1 nd4v0x2 1 d->z 310 111
2 oai21v0x6 4 b->z 395 85
3 iv1v0x12 1 a->z 441 46
4 oai21v0x6 4 a2->z 537 96
5 iv1v0x12 1 a->z 583 46
6 oai21v0x6 4 a2->z 661 78
7 xooi21v0x05 1 b->z 822 161
8 xor2v0x2 1 a->z 925 103
9 xor3v1x2 1 c->z 1012 87
10 oai21v0x3 1 b->z 1074 62
11 oai31v0x2 2 b->z 1152 78
12 iv1v0x4 1 a->z 1202 50
13 cgi2v0x2 2 c->z 1301 99
14 iv1v0x4 1 a->z 1355 54
15 cgi2v0x3 2 c->z 1439 84
16 iv1v0x4 1 a->z 1489 50
17 cgi2v0x2 2 c->z 1586 97
18 iv1v0x4 1 a->z 1641 55
19 cgi2v0x3 2 c->z 1724 83
20 iv1v0x4 1 a->z 1779 55
21 cgi2v0x3 2 c->z 1880 101
22 iv1v0x8 1 a->z 1932 52
23 cgi2v0x3 2 a->z 2032 100
24 iv1v0x6 1 a->z 2081 49
25 cgi2v0x3 2 c->z 2160 79
26 an2v0x6 2 b->z 2266 106
27 an2v0x6 2 b->z 2386 120
28 xaon21v0x3 0 a2->z 2523 137
r 15 |
| 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 |
| synthesis 14 | 2931 | 1400 | 562 | 55% | 104 | 38 | 3-XOR gate, 1/2 stage delays |
| synthesis 15 | 2886 | 1390 | 536 | 56% | 109 | 40 | 3-XOR/XNOR gates as 2×2-I/P gates |
| synthesis 16 | 2665 | 1514 | 538 | 60% | 136 | 46 | x3 drive strength cells |
| synthesis 17 | 2567 | 1571 | 540 | 61% | 155 | 49 | x4 drive strength cells |
| synthesis 18 | 2523 | 1611 | 540 | 62% | 167 | 49 | x6 drive strength cells |
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