Microelectronics: Circuit Analysis and Design, 4th edition Chapter 1
By D. A. Neamen Problem Solutions
______________________________________________________________________________________
Chapter 1
BT e−
gE
/ 2
kT
=
in
1.1
3/ 2
(a) Silicon
(
(i)
n
i
=
5.23 10
15
×
)(
3/ 2
250
)
exp
=
=
n
i
19
×
2.067 10 exp 25.58
1.61 10 cm
−
×
−
8
3
[
]
(ii)
n
i
=
(
5.23 10
15
×
)(
350
)
3/ 2
exp
=
=
n
i
19
3.425 10 exp
3.97 10 cm
3
−
×
×
11
[
18.27
−
]
⎡
⎢
⎢
⎣
⎡
⎢
⎢
⎣
1.1
−
(
)(
2 86 10
6
−
×
250
)
1.1
−
(
)(
2 86 10
6
−
×
350
)
⎤
⎥
⎥
⎦
⎤
⎥
⎥
⎦
(i)
(b) GaAs
)(
(
(
)
8.301 10
17
6.02 10 cm
3
2.10 10
14
=
=
n
i
=
×
×
×
n
i
3/ 2
exp
⎡
⎢
⎢
⎣
]
32.56
−
250
)
[
exp
3
−
(ii)
n
i
=
=
=
n
i
×
2.10 10
14
)(
(
(
)
1.375 10
18
1.09 10 cm
8
×
×
350
)
[
exp
3
−
3/ 2
exp
⎡
⎢
⎢
⎣
]
23.26
−
1.4
−
(
)(
2 86 10
6
−
×
250
)
⎤
⎥
⎥
⎦
1.4
−
(
)(
2 86 10
6
−
×
350
)
⎤
⎥
⎥
⎦
______________________________________________________________________________________
1.2
a.
3/ 2 exp
BT
=
n
i
−⎛
⎜
2
⎝
Eg
kT
⎞
⎟
⎠
10
12
=
5.23 10
15
×
T
3/ 2
exp
1.91 10
×
−
4
=
T
3/ 2
exp
By trial and error,
b.
10 cm
−
=
9
in
T ≈
3
10
9
=
5.23 10
15
×
T
3/ 2
exp
1.91 10
×
7
−
=
T
3/ 2
exp
1.1
T−
2(86 10 )( )
6
⎛
−
⎜
×
⎝
6.40 10
3
⎞
⎟
⎠
×
T
⎛
−⎜
⎝
368 K
1.1
−
(
2 86 10
6
−
×
⎛
⎜
⎜
⎝
6.40 10
3
⎞
⎟
⎟
⎠
)(
T
)
⎛
−⎜
⎝
268 K
×
T
⎞
⎟
⎠
⎞
⎟
⎠
By trial and error,
______________________________________________________________________________________
T ≈
°
Microelectronics: Circuit Analysis and Design, 4th edition Chapter 1
By D. A. Neamen Problem Solutions
______________________________________________________________________________________
1.3
Silicon
(a)
n
i
=
=
=
n
i
(b)
n
i
=
=
=
n
i
(c)
n
i
=
=
=
n
i
×
5.23 10
15
(
(
5.23 10
18
8.79 10
10
−
×
×
)(
100
)
exp
cm
3
−
[
3/ 2
)
exp
63.95
−
⎡
⎢
⎢
⎣
]
1.1
−
(
)(
100
2 86 10
6
−
×
)
⎤
⎥
⎥
⎦
×
5.23 10
15
(
(
2.718 10
19
1.5 10 cm
)(
)
×
10
×
300
)
exp
3
−
3/ 2
exp
⎡
1.1
−
⎢
(
)(
2 86 10
6
−
⎢
⎣
]
21.32
−
×
[
×
5.23 10
15
(
)(
(
)
5.847 10
19
×
1.63 10 cm
14
×
500
)
[
exp
3
−
3/ 2
exp
⎡
1.1
−
⎢
(
)(
2 86 10
6
−
⎢
⎣
]
12.79
−
×
⎤
⎥
⎥
⎦
300
)
⎤
⎥
⎥
⎦
500
)
Germanium.
(
1.66 10
15
(a)
n
i
=
×
)(
100
)
3/ 2
exp
n
i
=
35.9 cm
3
−
(b)
n
i
=
(
1.66 10
15
×
)(
300
)
3/ 2
exp
n
i
=
2.40 10 cm
×
13
3
−
(c)
n
i
=
(
1.66 10
15
×
)(
500
)
3/ 2
exp
⎡
⎢
⎢
⎣
⎡
⎢
⎢
⎣
⎡
⎢
⎢
⎣
0.66
−
)(
100
6
−
×
(
2 86 10
)
⎤
⎥
⎥
⎦
=
(
1.66 10
18
×
)
exp 38.37
−
[
]
0.66
−
)(
6
−
×
(
2 86 10
300
)
0.66
−
)(
6
−
×
(
2 86 10
500
)
⎤
⎥
⎥
⎦
⎤
⎥
⎥
⎦
=
(
8.626 10
18
×
)
exp
[
−
12.79
]
=
(
1.856 10
19
×
)
exp
[
−
7.674
]
n
i
=
8.62 10 cm
×
15
3
−
______________________________________________________________________________________
1.4
n
2
i
n
o
n
2
i
n
o
=
=
2
)
13
10
15
(
4.2
(
5.1
×
10
×
10
10
15
=
76.5
×
10
11
cm 3−
10
2
)
=
25.2
×
10
5
cm 3−
(a) n-type;
1510=on
3−
cm ;
p
o
=
(b) n-type;
1510=on
3−
cm ;
p
o
=
______________________________________________________________________________________
Microelectronics: Circuit Analysis and Design, 4th edition Chapter 1
By D. A. Neamen Problem Solutions
______________________________________________________________________________________
1.5
(a) p-type;
1610=op
3−
cm ;
n
=
o
n
2
i
p
o
(b) p-type;
1610=op
3−
cm ;
n
=
o
=
=
26
)
(
8.1
10
16
×
10
=
24.3
×
10
−
4
cm 3−
n
2
i
p
o
(
4.2
10
16
×
10
13
2
)
=
76.5
×
10
10
cm 3−
______________________________________________________________________________________
1.6
(a) n-type
(b)
N
=
−
3
n
o
p
o
=
d
n
2
i
n
o
N
16
5 10 cm
= ×
(
)
2
1.5 10
10
×
5 10
16
×
16
−
=
3
d
=
n
o
= ×
(c)
From Problem 1.1(a)(ii)
)2
5 10 cm
in
(
op
=
3.97 10
11
×
5 10
16
×
=
4.5 10 cm
×
3
−
3
3.97 10 cm
×
11
−
3
=
=
3.15 10 cm
×
6
3
−
______________________________________________________________________________________
1.7
(a) p-type;
5×=op
1610
3−
cm ;
n
(b) p-type;
5×=op
1610
3−
cm ;
n
=
=
o
o
2
)
10
(
5.1
10
×
16
5
10
×
(
8.1
10
×
16
10
5
×
26
)
=
=
n
2
i
p
o
n
2
i
p
o
=
5.4
×
10
3
cm 3−
=
48.6
×
10
−
5
cm 3−
______________________________________________________________________________________
1.8
a
N
(a) Add boron atoms
1710
(b)
10
×
17
10
×
2×=
(
5.1
2
p
= o
n
2
i
p
(c)
=
=
n
o
o
3−
cm
)
10
2
=
125.1
×
10
3
cm 3−
______________________________________________________________________________________
1.9
(a)
= ×
3
−
n
o
p
o
=
=
cm
5 10
15
(
1.5 10
10
×
5 10
15
×
n-type
5 10
15
n
2
i
n
o
p
N
2
)
⇒ =
p
o
4.5 10
4
×
cm−
3
3
d
o
n
n
o
cm−
= ×
⇒> o
≅
(b)
(c)
______________________________________________________________________________________
Microelectronics: Circuit Analysis and Design, 4th edition Chapter 1
By D. A. Neamen Problem Solutions
______________________________________________________________________________________
1.10
a. Add Donors
b. Want p
)(
So
6
exp
n N
/
2
=
i
21
7 10
= ×
7 10 cm
6
(
10
B T
2
= ×
dN
in
2
=
=
15
3
−
o
d
3
3
−
10 cm
=
)
7 10
15
×
Eg
−⎛
⎜
kT
⎝
⎞
⎟
⎠
)
7 10
×
21
=
(
5.23 10
15
×
2
3
T
exp
⎛
⎜
⎜
⎝
1.1
−
86 10
6
−
×
(
)(
T
)
⎞
⎟
⎟
⎠
°
T ≈
324 K
By trial and error,
______________________________________________________________________________________
1.11
(a)
mA
=Ε
=
A
I σ
A
Ε
ρ
=
I
(
)(
)(
)
I
10 5
15.0
105.1
−
=⇒
)(
(
)
I
3
10
2.1
4.0
−
×
ρ
=Ε⇒
)
(
A
2
10
×
=
−
4
(b)
=
4.2
V/cm
______________________________________________________________________________________
1.12
J
=⇒Ε=
σσ
67.6
=
=
J
Ε
N
d
120
18
σ
e
μ
n
−
) 1
(
cm
−Ω
(
)
67.6
)(
19
10
1250
−
×
=
(
6.1
μσ
n
Ne
≅
d
=⇒
=
33.3
×
16
10
cm 3−
)
______________________________________________________________________________________
1.13
(a)
=⇒
cm 3−
69.7
15
10
≅
ρ
N
×
=
1
Ne
μ
n
Ε
ρ
d
d
=
1
e
ρμ
)(
160
n
(
65.0
(
6.1
10
×
) 104
=
19
−
1
)(
1250
V/cm
)(
65.0
)
(b)
J
=
=Ε⇒
J
ρ
=
______________________________________________________________________________________
1.14
(a)
=⇒
cm 3−
375.9
Ne
15
10
N
×
=
=
≅
μσ
n
d
d
5.1
19
−
(b)
N
a
=
σ
e
μ
p
=
(
6.1
×
σ
e
μ
n
8.0
)(
19
10
400
−
(
6.1
×
10
=
25.1
×
)
)(
1000
10
)
cm 3−
16
______________________________________________________________________________________
1.15
(a) For n-type,
σ μ
n
For
dN
10
10
15
19
≤
)
(
0.1
(b)
σ σ
=
⇒
______________________________________________________________________________________
(
1.6 10
1.36
⇒
J
≤ ≤
≤
1.36 10
3
d
cm
0.136
(
×
A cm
/
2
d
1.36 10
)(
σ
≤
×
e N
8500
≤
=
Ω −
) 1
cm
N
E
19
−
≅
=
×
J
)
−
−
3
4
Microelectronics: Circuit Analysis and Design, 4th edition Chapter 1
By D. A. Neamen Problem Solutions
______________________________________________________________________________________
1.16
cm /s
5.32
7.11
=
=
2
)(
450
(
.0
)
)
=nD
J
n
=
eD
×
10
19
−
52
A/cm 2
)(
026
1250
dn
(
6.1
dx
=
n
⎛
)
⎜⎜
⎝
(
cm 2 /s;
=pD
026.0
16
12
10
10
⎞
)(
−
5.32
−=⎟⎟
001.00
−
⎠
12
16
10
10
⎛
)
⎜⎜
001.00
⎝
19
−
−
p
p
J
×
−
10
eD
−=
−=
dp
dx
(
6.1
)(
7.11
Total diffusion current density
______________________________________________________________________________________
1.17
⎞
−=⎟⎟
⎠
A/cm 2
A/cm 2
72.18
−=J
72.18
7.70
−=
52
−
⎛
⎜
⎜
⎝
)
15
exp
p
15
1
⎞
⎟
⎟
⎠
)(
⎛
−
)
⎜
⎜
L
⎝
)(
15 10
10 10
4
−
x L
/
19
−
×
p
−
L
x
p
exp
⎞
⎟
⎟
⎠
⎛
⎜
⎜
⎝
⎞−
x
⎟
⎟
L
⎠
p
J
p
= −
eD
p
= −
eD
p
dp
dx
(
10
(
1.6 10
×
J
p
=
−
e
J
2.4
=
p
x = 0
x
x
2
2.4
2.4
pJ =
10 m
μ=
30 m
μ=
2.4 A/cm
=
=
(a)
(b)
(c)
______________________________________________________________________________________
1.18
a.
0.883 A/cm
0.119 A/cm
e−
1
e−
3
pJ
pJ
=
=
N
=
17
−
2
2
3
a
17
3
−
=
10 cm
p
⇒ =
o
)26
10 cm
(
1.8 10
×
n
2
i
p
10
17
o
n
3.24 10
×
δ
+
=
p
10
10
15
17
+ ⇒ =
+
δ
=
⇒ =
n
o
5
−
3.24 10 cm
×
5
−
3
−
n
10 cm
10
15
+ ⇒ =
p
1.01 10 cm
×
15
17
−
3
3
−
n
o
=
b.
n
p
=
=
n
o
p
o
______________________________________________________________________________________
1.19
V
bi
=
V
T
ln
⎛
⎜⎜
⎝
d
NN
2
i
a
n
⎞
⎟⎟
⎠
(a) (i)
=biV
(
.0
026
)
ln
(ii)
=biV
(
.0
026
)
(iii)
=biV
(
.0
026
)
ln
ln
10
)
2
15
)
(
5
17
15
×
×
10
10
×
(
5.1
(
10
5
×
(
5.1
×
(
)(
10
10
(
10
5.1
10
)(
5
10
)(
10
)
10
10
)
⎤
⎥
⎥
⎦
)
×
18
18
2
2
⎡
⎢
⎢
⎣
⎡
⎢
⎢
⎣
⎡
⎢
⎢
⎣
15
)
⎤
⎥
⎥
⎦
=
.0
661
V
=
.0
739
V
⎤
⎥
⎥
⎦
=
.0
937
V
Microelectronics: Circuit Analysis and Design, 4th edition Chapter 1
By D. A. Neamen Problem Solutions
______________________________________________________________________________________
(b) (i)
=biV
(
026.0
)
ln
=
13.1
V
15
)
⎤
⎥
⎥
⎦
17
15
15
(
5
10
×
(
8.1
(
5
10
×
(
8.1
×
(
)(
10
10
(
8.1
10
×
)(
10
5
×
)
26
10
×
)(
10
)
26
10
)
⎤
⎥
⎥
⎦
)
⎤
⎥
⎥
⎦
26
)
=
18
18
⎡
⎢
⎢
⎣
⎡
⎢
⎢
⎣
⎡
⎢
⎢
⎣
=
21.1
V
41.1
V
(ii)
=biV
(
026.0
)
ln
(iii)
=biV
(
026.0
)
ln
______________________________________________________________________________________
1.20
⎛
⎜⎜
⎝
d
NN
2
i
a
n
⎞
⎟⎟
⎠
V
bi
=
V
T
ln
or
N
=
a
)
(
2
n
i
N
d
⎛
exp
⎜⎜
⎝
V
bi
V
T
⎞
=⎟⎟
⎠
2
)
(
10
5.1
×
16
10
⎛
exp
⎜
⎝
.0
.0
712
026
⎞
=⎟
⎠
76.1
×
10
16
cm 3−
______________________________________________________________________________________
1.21
N N
a
n
2
i
ln
⎛
⎜
⎝
cm
10
15
cm
10
18
3
−
3
−
,
,
d
=
⎞
⎟
⎠
V
bi
V
bi
V
bi
=
V
T
N
N
a
a
=
=
For
For
(
0.026 ln
)
=
=
0.637
0.817
⎡
⎢
⎢
⎣
V
V
(
)16
N
10
(1.5 10 )
1
0 2
×
a
⎤
⎥
⎥
⎦
______________________________________________________________________________________
1.22
(0.026)
kT
=
⎞
⎟
⎠
T
⎛
⎜
300
⎝
200
250
300
350
400
450
500
kT
0.01733
0.02167
0.026
0.03033
0.03467
0.0390
0.04333
(T)3/2
2828.4
3952.8
5196.2
6547.9
8000.0
9545.9
11,180.3
Microelectronics: Circuit Analysis and Design, 4th edition Chapter 1
By D. A. Neamen Problem Solutions
______________________________________________________________________________________
in
=
(
2.1 10
14
×
)(
T
3/ 2
)
exp
⎛
⎜
⎜
⎝
1.4
−
(
2 86 10
6
−
×
)(
T
)
⎞
⎟
⎟
⎠
V
bi
=
V
T
ln
T
200
250
300
350
400
450
500
d
⎞
⎟
⎠
N N
a
n
2
i
⎛
⎜
⎝
ni
1.256
6.02 × 103
1.80 × 106
1.09 × 108
2.44 × 109
2.80 × 1010
2.00 × 1011
Vbi
1.405
1.389
1.370
1.349
1.327
1.302
1.277
______________________________________________________________________________________
1.23
V
R
V
bi
⎡
⎢
⎢
⎣
1/ 2
−
⎞
⎟
⎠
(
1.5 10
16
)(
×
(
1.5 10
1/ 2
1
×
−
4 10
×
)
10
2
15
)
⎤
⎥
⎥
⎦
=
0.684 V
C
=
C
jo
j
⎛
1
+⎜
⎝
biV
=
(
0.026 ln
)
(a)
jC
=
(b)
jC
=
(c)
jC
=
(
(
(
)
)
⎛
0.4 1
⎜
⎝
⎛
0.4 1
⎜
⎝
⎛
0.4 1
⎜
⎝
)
+
+
+
⎞
⎟
⎠
⎞
⎟
⎠
⎞
⎟
⎠
0.684
3
0.684
5
0.684
=
0.255 pF
−
1/ 2
−
1/ 2
=
0.172 pF
=
0.139 pF
______________________________________________________________________________________
1.24
(a)
C
j
=
C
jo
/
1 2
−
⎛
1
+⎜
⎝
V
R
V
bi
⎞
⎟
⎠
For VR = 5 V,
jC
=
.
⎛
(0 02) 1
⎜
⎝
+
For VR = 1.5 V,
C
=
j
.
⎛
(0 02) 1
⎜
⎝
+
5
⎞
⎟
.
0 8
⎠
.
1 5
.
0 8
/
1 2
−
=
.
0 00743
p
F
−
/
1 2
⎞
⎟
⎠
=
.
0 0118
p
F
Microelectronics: Circuit Analysis and Design, 4th edition Chapter 1
By D. A. Neamen Problem Solutions
______________________________________________________________________________________
.
0 00743 0 0118
pF
=
=
)
.
+
2
+
(
final
)
v
C
(
initial
.
0 00962
)
v
C
−
(
)
final
)
e τ−
t /
RC RC avg
(
)
=
(47 10 )(0 00962 10 )
1
2
−
×
×
3
.
j
C avg
(
( )
t
j
(
=
=
v
C
v
C
where
=
τ
or
.
4 52 10
=
τ
( )
Cv
.
t
Then
1 5
5
re
1 /
1.5
t
=
1
5.44 10
×
=
=
×
τ
+
10
−
s
0
= +
⇒ =
t
1
τ
it /
τ−
(
)
5 0
−
5
⎛
⎜
1.5
⎝
e
⎞
⎟
⎠
ln
s
10
−
(b) For VR = 0 V, Cj = Cjo = 0.02 pF
1/ 2
−
⎞
⎟
⎠
For VR = 3.5 V,
3.5
0.8
⎛
0.02 1
⎜
⎝
0.02 0.00863
jC
=
+
+
(
)
=
0.0143
pF
=
p
0.00863
F
)
(
=
(
v
C
jC avg
)
jRC avg
=
=
τ
(
( )
final
v
t
C
e
3.5 5 (0 5)
−
= +
−
t
8.09 10
×
=
=
10
−
2
s
6.72 10
×
(
)
initial
v
+
C
(
e
5 1
t
/
−
τ
−
t
)
(
so that
______________________________________________________________________________________
1.25
(
=
s
v
C
final
e τ−
/t
−
)
10
−
)
)
/
τ
2
2
2
C
j
=
C
jo
For
1=RV
+
1
⎛
⎜⎜
⎝
V,
2/1
−
R
V
V
bi
⎞
⎟⎟
⎠
;
=biV
(
.0
026
)
ln
⎡
⎢
⎢
⎣
(
10
5
×
(
5.1
×
15
)(
10
)
10
10
17
2
)
=
.0
739
V
⎤
⎥
⎥
⎦
57.6
MHz
=jC
For
3=RV
V,
=jC
1
1
60.0
1
+
739.0
60.0
3
739
.0
+
For
5=RV
V,
=jC
1
60.0
5
739
.0
+
=
.0
391
pF
=
267.0
pF
=
215.0
pF
(a)
f
o
=
1
2
π
LC
=
(b)
f
o
=
2
π
(
5.1
×
1
)(
3
.0
×
10
−
391
×
10
(
5.1
267
×
10
12
−
)
=⇒
f
o
2
π
1
)(
3
.0
−
10
12
−
)
95.7
=⇒
f
o
MHz