8.15 RC models of the two circuits are shown below. The Elmore delay of the unta-
pered stack is [15*(1/30) + 15*(2/30) + 15*(3/30) + 38*(4/30)]RC = 8.07 RC. The
Elmore delay of the tapered stack is [22*(1/30) + 20*(1/27 + 1/30) + 18*(1/24 + 1/27
+ 1/30) + 30*(1/22 + 1/24 + 1/27 + 1/30)]RC = 8.88 RC. The untapered design is
faster.
R/30 R/30 R/30 R/30
R/30 R/27 R/24 R/22
22C 20C 18C (22+8)C
15C 15C 15C (30+8)C
Untapered
Tapered
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