16. Frequency
1s is related to 1Hz
Frequency = 1/time
How many things per second?
How fast can the circuit be clocked at?
17. Value
Symbol
Name
Hz
Term
s
s
second
1
1 Hz
10−1 s
ds
decisecond
10
10−2 s
cs
centisecond
100
10−3 s
ms
millisecond
1000
1 KHz
10−6 s
µs
microsecond
1000000
1 MHz
10−9 s
ns
nanosecond
1000000000
1 GHz
10−12 s
ps
picosecond
1000000000000 1 THz
10−15 s
fs
femtosecond
10−18 s
as
attosecond
10−21 s
zs
zeptosecond
10−24 s
ys
yoctosecond
18. Problem Set
1. What is the output of the following circuit for each clock
assuming the flip-flops are initialized as follows: ff0 = 1, ff1 = 0,
ff2 = 0, and ff3 = 0. Does the sequence ever end or repeat? What
might this be good for? What’s the critical path?
ff0
clk
ff1
ff2
ff3