§12.3超前进位加法器 超前进位算法的基础 Ci+1=8,+P,C S,=P©c C1=8o+Po·Co C2=81+p1·C1 C3=82+P2·C2 C4=83+P3·C3 C2=81+P1(8o+P0Co)=81+P18o+p1·poCo C3=82+P2(81+P180+p1·poCo) =82+P281+P2'P‘8o+P2P1'PoCo C4=83+P3(82+P2'81+P2P18o+P2p1PoCo) =83+P3·82+P3'P281+P3P2P18o+P3·P2P1P0Co 2018-9-5 第12章CMOS VLSI:运算电路 13 §12.3超前进位加法器 4位CLA进位的逻辑电路 用CLA进位电路计算和 co Po S,=p,⊕C 90* co Po ● co 50 90 Po 91 P P1 S1 91 CLA Network C2 2， 92 S2 P3 93 53 P3 93 2018-9-5 第12章CMOS VLSI运算电路 142018-9-5 第12章 CMOS VLSI运算电路 13 §12.3 超前进位加法器 超前进位算法的基础 3 2 2 2 4 3 3 3 1 0 0 0 2 1 1 1 c g p c c g p c c g p c c g p c = + ⋅ = + ⋅ = + ⋅ = + ⋅ 2 1 1 0 0 0 1 1 0 1 0 0 c = g + p ⋅(g + p ⋅c ) = g + p ⋅ g + p ⋅ p ⋅c 2 2 1 2 1 0 2 1 0 0 3 2 2 1 1 0 1 0 0 ( ) g p g p p g p p p c c g p g p g p p c = + ⋅ + ⋅ ⋅ + ⋅ ⋅ ⋅ = + ⋅ + ⋅ + ⋅ ⋅ 3 3 2 3 2 1 3 2 1 0 3 2 1 0 0 4 3 3 2 2 1 2 1 0 2 1 0 0 ( ) g p g p p g p p p g p p p p c c g p g p g p p g p p p c = + ⋅ + ⋅ ⋅ + ⋅ ⋅ ⋅ + ⋅ ⋅ ⋅ ⋅ = + ⋅ + ⋅ + ⋅ ⋅ + ⋅ ⋅ ⋅ i i i i i i i c = g + p ⋅c s = p ⊕c + 1 2018-9-5 第12章 CMOS VLSI运算电路 14 §12.3 超前进位加法器 4位CLA进位的逻辑电路 用CLA进位电路计算和 i i i s = p ⊕ c