15 RC MODELS OF THE TWO CIRCUITS ARE SHOWN BELOW

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