
Adders with Redundant Digit Set
97
(g7,a7) (g6,a6) (g5,a5) (g4a4) (g3 a3) (g2a2) (gl,al)
(go, ao )
Prefix network
(Notes: no
C in
input;
last level consists
of "circle" modules)
1------
g(7,0)
g(60) g(5,0) g(4,0) g(30) g(2,0) g(1,0)
a(6,0) a(50) a(40) a(30) a(20 ) a(10)
noaooo~ T X T T T T I Tl/
~ I'[ I'l I'1 ]'1 I'1 I'1
:
c 7 c 6 ] J Co
P P5 P P3~ P2~ Pl~ P0~
s 7 s 6 s 5 s 4 s 3 s 2 s 1 s 0
FIGURE 2.29 Implementing ones' complement adder with prefix network. (Modules to
obtain Pi,
gi,
and a i signals not shown.)
Figure 2.20, this end-around carry would significantly increase the ...