EEL6323-S10-HLec018-Adders-4spp

EEL6323-S10-HLec018-Adders-4spp - Lecture 18: Adders...

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1 Lecture 18: Adders Single-bit Addition Carry-Ripple Adder Carry-Skip Adder Carry-Select Adder Carry-Lookahead Adder Tree Adder Reading: Chapter 10, W&H Carry Generation and Propagation Define 3 new variables that depend only on A and B – Generate: C out = 1 independent of C •G = A •B – Propagate: C out = C •P = A B – Kill: C out = 0 independent of C • K = ~A • ~B S = P C in C out = G + P C in Carry Chain Carry of Mirror Adder Manchester Carry Chain C 0 =G 0:0 =G 0 C 1 =G 1:0 =G 1 + P 1 C 0 C 2 =G 2:0 =G 2 + P 2 (G 1 + P 1 C 0 ) C 3 =G 3:0 =G 3 + P 3 (G 2 + P 2 (G 1 + P 1 C 0 )) Group PG Logic G i:0 =G i +P i G i-1:0 P i:0 =P i P i-1:0 (C i =G i:0 ) or C i =G i +P i C i-1 Sum Logic Bitwise PG Logic G i =A i B i P i = (A i + B i ) S i =P i + G i-1:0
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2 PG network for Manchester Carry Chain Manchester Carry Chain P i + 1 G i + 1 C i Inverter/Sum Row Propagate/Generate Row P i G i C i - 1 C i + 1 V DD GND R 1 C 1 R 2 C 2 R 3 C 3 R 4 C 4 R 5 C 5 R 6 C 6 Out M 0 M 1 M 2 M 3 M 4 M C Discharge Transistor 12 3 4 5 6 Carry-Bypass Adder FA FA FA FA P 0 G 0 P 1 G 1 P 2 G 2 P 3 G 3 C 3
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This note was uploaded on 01/17/2011 for the course EEL 6323 taught by Professor Bashirullah during the Spring '08 term at University of Florida.

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EEL6323-S10-HLec018-Adders-4spp - Lecture 18: Adders...

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