Consider the following circuit where the input transistor ha

Consider the following circuit where the input transistor has Wn-1um, Wp 2um. Assume =1 and that the optimum fanout f-4. Cout-1pF Cin-10 a) Calculate the optimum number of stages N to minimize the propagation delay of the chain

Solution

a) F = CL/Cg = 100

No. of stages N = ln(F) - 1 = ln(100) - 1 = 3.6 ~ 4

                                N = 4

b) Size of Nth inverter = K^4 * size of first inverter

c) f = (F)^(1/N) = 3.16

Delay of chain = N*t*(f + gamma) = (4)(20ps)(4.16) = 332.8ps