111adder
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Transcript of 111adder
Adder comparisons and New (1,1,1)adder
Peeyush Pashine
2011H140033H
Brent Kung adder
Sklansky adder
c1
(p2, g2)(p3, g3)(p4, g4)(p5, g5)(p6, g6)(p7, g7)(p8, g8)
c2c3c4c5c6c7c8
(p1, g1)
Skalnsky adder 16 bit
1:
0
2:
0
3:
0
3:
2
5:
4
7:
6
9:
8
11:1
0
13:1
2
15:1
4
6:
4
7:
4
10:
8
11:
8
14:1
2
15:1
2
12:
8
13:
8
14:
8
15:
8
0123456789101112131415
15:014:013:0 12:011:010:0 9:0 8:0 7:0 6:0 5:0 4:0 3:0 2:0 1:0 0:0
Ladner fischer adder
1:03:25:47:69:811:1013:12
3:07:411:815:12
5:07:013:815:8
15:14
15:8 13:0 11:0 9:0
0123456789101112131415
15:0 14:013:012:0 11:010:0 9:0 8:0 7:0 6:0 5:0 4:0 3:0 2:0 1:0 0:0
Kogge stone adder
1:02:13:24:35:46:57:68:79:810:911:1012:1113:1214:1315:14
3:04:15:26:37:48:59:610:711:812:913:1014:1115:12
4:05:06:07:08:19:210:311:412:513:614:715:8
2:0
0123456789101112131415
15:014:013:0 12:011:010:0 9:0 8:0 7:0 6:0 5:0 4:0 3:0 2:0 1:0 0:0
7
Classical prefix adders
12345678
12:13:14:16:17:18:1 5:1
Brent-Kung:
Logical levels: 2log2n–1
Max fanouts: 2
Wire tracks: 1
12345678
12:13:14:16:17:18:1 5:1
Kogge-Stone:
Logical levels: log2n
Max fanouts: 2
Wire tracks: n/2
12345678
12:13:14:16:17:18:1 5:1
Sklansky:
Logical levels: log2n
Max fanouts: n/2
Wire tracks: 1
Knowles 2,1,1,1
Knowles 4,2,1,1
Topology of some prefix adders
Brent-Kung topology(Minimum fan-out)
Ladner-Fischer topology(Minimum depth, high fanout)
Knowles topologies(Varied fan-out at each level )
Prefix adder taxonomy
New (1,1,1) Adder
2345678
2:13:14:16:17:18:1 5:1
19101112
19:110:111:112:1