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Table 4 Theoretical (i.e., approximate) cycle time estimates of various 32-bit asynchronous RCAs corresponding to different carry chain lengths

From: Area/latency optimized early output asynchronous full adders and relative-timed ripple carry adders

Full adder constituting the RCA; RCA type is given alongside

Theoretical cycle time (in ns) for RCAs corresponding to various carry-propagation chain lengths

4 Full adders

8 Full adders

16 Full adders

32 Full adders

Singh (1981)—strong

29.22

29.22

29.22

29.22

Sparsø and Staunstrup (1993)—strong

18.52

18.52

18.52

18.52

Toms (2006)—strong

18.08

18.08

18.08

18.08

Sparsø and Staunstrup (1993)—weak

2.06

4.12

8.24

16.48

Toms and Edwards (2010)—weak

2.42

4.83

9.66

19.32

Folco et al. (2005)—weak

1.75

3.5

7

14

Balasubramanian and Edwards (2008c)—weak

0.83

1.38

2.49

4.71

Balasubramanian (2015)—weak

0.62

1.04

1.87

3.53

Balasubramanian (2011)—early output

0.58

0.97

1.74

3.29

Seitz (1979) Early output—relative-timed

0.82

1.47

2.78

5.40

AOPT_EO_FA (proposed)—relative-timed

0.47

0.85

1.61

3.12

LOPT_EO_FA (proposed)—relative-timed

0.45

0.82

1.55

3