1Conditional-SumAdderLecture 5 (portrait slides)Parallel Prefix NetworkAddersConditionalAdder22222xi+3yi+3c=0c=122xi+2yi+2c=0c=111113c=03c=12222xi+1yi+1c=0c=122xiyic=0c=111113c=03c=12211335c=15c=03-level Conditional-Sum Adder1+12+14+1Brent-KungParallel Prefix NetworkAdder38-bit Brent-Kung Parallel Prefix Networkx0x1x2x3x4x5x6x7s0s1s2s3s4s5s6s74 –bit B-K PPN4-bit Brent-Kung Parallel Prefix Networkx1’x3’s1’s3’2 –bit B-K PPNx5’x7’s5’s7’4GP GP GP GP GP GP GPGPx7y7x6y6x5y5x4y4x3y3x2y2x1y1x0y0g7,p7g6,p6g5,p5g4,p4g3,p3g2,p2g1,p1g0,p0ccc cc cccc ccg[0,0]p[0,0]g[0,1]p[0,1]g[0,2]p[0,2]g[0,3]p[0,3]g[0,4]p[0,4]g[0,5]p[0,5]g[0,6]p[0,6]g[0,7]p[0,7]Cc0CCCC CC CSSSS SS SSc7p7c6p6c5p5c4p4c3p3c2p2c1p1p0s7s6s5s4s3s2s1s0c8Brent-Kung Parallel Prefix NetworkcriticalpathGPcCSgi= xiyipi= xi⊕ yig = g” + g’ p”p = p’ p”ci+1= g[0,i]+ c0 p[0,i]si= pi⊕ ci1 gate delay2 gate delays2 gate delays1 gate
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