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+3.3V
0V
C
40pF
V
in
V
out
I
C
0
0
+3.3V
V
out
(t)
1ns
0
0
0.132A
I
C
(t)
1ns
The current waveform just looks like the square pulse shown, essentially the derivative of the
voltage waveform:
64 I
C
⋅
8.448 amp
=
If all 64 drivers switch at the same time, the total peak current will be:
I
C
0.132 amp
=
I
C
C
∆
V
∆
t
⋅
:=
∆
t
1.0 ns
⋅
:=
∆
V
3.3 volt
⋅
:=
C4
0
p
F
⋅
:=
(Use this value of 1.0 ns
shown in Fig. P6.31, not
the 0.8 ns in the problem
text.)
The average current to discharge each of the capacitive loads is just the dV/dt of the voltage
waveform multiplied by the capacitance of the load:
Problem 1:
Problem 6.31 of Jaeger and Blalock.
µ
W1
0
6
−
watt
⋅
:=
mW
10
3
−
watt
⋅
:=
ns
10
9
−
sec
⋅
:=
M
Ω
10
6
ohm
⋅
:=
EE331 Devices and Circuits 1
Prof. R. B. Darling
Homework # 9 Solutions
First, define some useful units and constants:
µ
m1
0
6
−
m
⋅
:=
eV
1.602 10
19
−
⋅
joule
⋅
:=
ms
10
3
−
sec
⋅
:=
µ
s1
0
6
−
sec
⋅
:=
q
1.602 10
19
−
⋅
coul
⋅
:=
k
B
8.62 10
5
−
⋅
eV
⋅
K
1
−
⋅
:=
nm
10
9
−
m
⋅
:=
ε
rSiO2
3.9
:=
ε
o
8.854 10
14
−
⋅
farad
⋅
cm
1
−
⋅
:=
n
i
10
10
cm
3
−
⋅
:=
V
T
0.025 volt
⋅
:=
ε
rSi
11.7
:=
Ω
ohm
:=
k
Ω
10
3
ohm
⋅
:=
EE331 HW#9 Solutions
Page 1
R. B. Darling
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D
V
DD
V
OL
−
R
:=
I
D
6.2
µ
A
=
P
D
V
DD
I
D
⋅
:=
P
D
15.59
µ
W
=
Problem 3:
Problem 6.53 (a) of Jaeger and Blalock.
Find the values of R, W, and L for the resistively loaded nMOS inverter:
V
DD
3.0 volt
⋅
:=
V
OL
0.30 volt
⋅
:=
I
DD
33
µ
A
⋅
:=
R
V
DD
V
OL
−
I
DD
:=
R
81.8 k
Ω
=
k
n
60
µ
A
⋅
volt
2
−
⋅
:=
V
Tn
0.75 volt
⋅
:=
WLratio
I
DD
k
n
V
DD
V
Tn
−
()
V
OL
⋅
0.5 V
OL
2
⋅
−
⎡
⎣
⎤
⎦
⋅
:=
WLratio
0.873
=
Choose
L
2.0
µ
m
⋅
:=
W
WLratio L
⋅
:=
W
1.746
µ
m
=
Problem 2:
Problem 6.39 (a,b) of Jaeger and Blalock.
(a)
V
OH
is just equal to the upper power supply rail, +2.5 Volts.
V
OL
is determined by setting the
current through the resistor equal to the nonsaturated current of the MOSFET:
k
n
100
µ
A
⋅
volt
2
−
⋅
:=
V
Tn
0.60 volt
⋅
:=
V
DD
2.5 volt
⋅
:=
R
200 k
Ω
⋅
:=
V
OL
0.25 volt
⋅
:=
(initial guess at root)
V
OL
root
V
DD
V
OL
−
R
k
n
3
1
⋅
V
DD
V
Tn
−
V
OL
⋅
1
2
V
OL
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 Winter '08
 Taicheng

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