Short Notes: Analog Circuits | Short Notes for Electronics and Communication - Electronics and Communication Engineering (ECE) PDF Download

Download, print and study this document offline
Please wait while the PDF view is loading
 Page 1


• Energy gap
???? G/si
=1.21- 3.6 × 10
-4
.T   ev
???? G/Ge
=0.785- 2.23 × 10
-4
.T   ev
? Energy gap depending on temperature 
• E
F
 = E
C
 - KT ln?
???? ???? ???? ???? ? = E
v
 + KT ln ?
???? ???? ???? ???? ? 
• No. of electrons  n = N
c
 e
-(E
c
-E
f
)/RT
         (KT in ev) 
• No. of holes  p = N
v
 e
-(E
f
-E
v
)/RT
• Mass action law  n
p
 = n
i
2
 = N
c
N
v
 e
-EG/KT
• Drift velocity  ???? d
 = µE  (for si ???? d
 = 10
7
 cm/sec)
• Hall voltage ???? H
 = 
B.I
w
e
 . Hall coefficient  R
H
 = 1/? .            ? ? charge density = qN
0
 = ne … 
• Conductivity  s = ?µ ;  µ = sR
H
 .
• Max value of electric field @ junction E
0
 =  -
q
?
si
N
d
. n
n0
 =  -
q
?
si
 N
A
. n
p0
 . 
• Charge storage @ junction  Q
+
 = - Q
-
 = qA x
n0
N
D
 =  qA x
p0
N
A
• Diffusion current densities  J
p
 = - q D
p
 
dp
dx
J
n
 = - q D
n
 
dn
dx
• Drift current Densities  = q(p µ
p
+ nµ
n
)E
• µ
p
 , µ
n
 decrease with increasing doping concentration .
•
D
n
µ
n
= 
D
p
µ
p
 = KT/q ˜ 25 mv @ 300 K 
• Carrier concentration in N-type silicon n
n0
 = N
D
 ;  p
n0
 = n
i
2
 / N
D
• Carrier concentration in P-type silicon p
p0
 = N
A
 ;  n
p0
 = n
i
2
 / N
A
• Junction built in voltage  V
0
 = V
T
 ln ?
???? ???? ???? ???? ???? ???? 2
? 
• Width of Depletion region  W
dep
 =  x
p
 + x
n
 = ?
2e
s
q
?
1
N
A
+
1
N
D
?(V
0
+ V
R
) 
* ?
2???? ???????? ???? = 12.93???? ???????????? ???????? ?  
•
x
n
x
p
 = 
N
A
N
D
 
• Charge stored in depletion region  q
J
 = 
q.N
A
 N
D
N
A
+N
D
 . A . W
dep
  
• Depletion capacitance  C
j
 = 
e
s
A
W
dep
 ;   C
j0
 = 
e
s
A
W
dep
/ V
R
=0
C
j
 = C
j0
/? 1 +
V
R
V
0
?
m
  C
j
 = 2C
j0
  (for forward Bias) 
• Forward current  I = I
p
+ I
n
 ;       I
p
 = Aq n
i
2
D
p
L
p
N
D
 ? ???? ???? /???? ???? - 1? 
I
n
 = Aq n
i
2
 
D
n
L
n
N
A
 ? ???? ???? /???? ???? - 1?  
• Saturation Current  I
s
 = Aq n
i
2
  ?
D
p
L
p
N
D
+
D
n
L
n
N
A
? 
• Minority carrier life time  t
p
 = L
p
2
 / D
p
  ;    t
n
 = L
n
2
 / D
n
Analog Circuits 
gradeu
gradeup
Page 2


• Energy gap
???? G/si
=1.21- 3.6 × 10
-4
.T   ev
???? G/Ge
=0.785- 2.23 × 10
-4
.T   ev
? Energy gap depending on temperature 
• E
F
 = E
C
 - KT ln?
???? ???? ???? ???? ? = E
v
 + KT ln ?
???? ???? ???? ???? ? 
• No. of electrons  n = N
c
 e
-(E
c
-E
f
)/RT
         (KT in ev) 
• No. of holes  p = N
v
 e
-(E
f
-E
v
)/RT
• Mass action law  n
p
 = n
i
2
 = N
c
N
v
 e
-EG/KT
• Drift velocity  ???? d
 = µE  (for si ???? d
 = 10
7
 cm/sec)
• Hall voltage ???? H
 = 
B.I
w
e
 . Hall coefficient  R
H
 = 1/? .            ? ? charge density = qN
0
 = ne … 
• Conductivity  s = ?µ ;  µ = sR
H
 .
• Max value of electric field @ junction E
0
 =  -
q
?
si
N
d
. n
n0
 =  -
q
?
si
 N
A
. n
p0
 . 
• Charge storage @ junction  Q
+
 = - Q
-
 = qA x
n0
N
D
 =  qA x
p0
N
A
• Diffusion current densities  J
p
 = - q D
p
 
dp
dx
J
n
 = - q D
n
 
dn
dx
• Drift current Densities  = q(p µ
p
+ nµ
n
)E
• µ
p
 , µ
n
 decrease with increasing doping concentration .
•
D
n
µ
n
= 
D
p
µ
p
 = KT/q ˜ 25 mv @ 300 K 
• Carrier concentration in N-type silicon n
n0
 = N
D
 ;  p
n0
 = n
i
2
 / N
D
• Carrier concentration in P-type silicon p
p0
 = N
A
 ;  n
p0
 = n
i
2
 / N
A
• Junction built in voltage  V
0
 = V
T
 ln ?
???? ???? ???? ???? ???? ???? 2
? 
• Width of Depletion region  W
dep
 =  x
p
 + x
n
 = ?
2e
s
q
?
1
N
A
+
1
N
D
?(V
0
+ V
R
) 
* ?
2???? ???????? ???? = 12.93???? ???????????? ???????? ?  
•
x
n
x
p
 = 
N
A
N
D
 
• Charge stored in depletion region  q
J
 = 
q.N
A
 N
D
N
A
+N
D
 . A . W
dep
  
• Depletion capacitance  C
j
 = 
e
s
A
W
dep
 ;   C
j0
 = 
e
s
A
W
dep
/ V
R
=0
C
j
 = C
j0
/? 1 +
V
R
V
0
?
m
  C
j
 = 2C
j0
  (for forward Bias) 
• Forward current  I = I
p
+ I
n
 ;       I
p
 = Aq n
i
2
D
p
L
p
N
D
 ? ???? ???? /???? ???? - 1? 
I
n
 = Aq n
i
2
 
D
n
L
n
N
A
 ? ???? ???? /???? ???? - 1?  
• Saturation Current  I
s
 = Aq n
i
2
  ?
D
p
L
p
N
D
+
D
n
L
n
N
A
? 
• Minority carrier life time  t
p
 = L
p
2
 / D
p
  ;    t
n
 = L
n
2
 / D
n
Analog Circuits 
gradeu
gradeup
• Minority carrier charge storage  Q
p
 = t
p
I
p
 ,  Q
n
 = t
p
I
n
     Q = Q
p
 + Q
n
 = t
T
I              t
T
 = mean transist time 
• Diffusion capacitance  C
d
 =  ?
???? ???? ???????? ???? ? I = t.g  ? C
d
 ? I. 
t? carrier life time ,  g = conductance = I /  ???????? ????  
• I
02
 = 2
(T
2
-T
1
)/10
 I
01
• Junction Barrier Voltage  V
j
 = V
B
 = V
r
 (open condition)
           = V
r
 - V (forward Bias) 
           =  V
r
 + V (Reverse Bias) 
• Probability of filled states above ‘E’  f(E) = 
1
1+e
(E-E
f
)/KT
  
• Drift velocity of  e
-
        ???? d
 = 10
7
 cm/sec 
• Poisson equation  
d
2
V
dx
2
 = 
-?
v
?
  = 
-nq
?
 ? 
dv
dx
 = E = 
-nqx
?
  
Transistor :- 
• I
E
 = I
DE
 + I
nE
• I
C
 = I
Co
 – a I
E
  ? Active region
• I
C
 = – a I
E
 + I
Co
 (1- e
V
C
/V
T
 )
Common Emitter :- 
• I
C
 = (1+ ß) I
Co
 + ßI
B
    ß = 
a
1-a
• I
CEO
 = 
I
Co
1-a
  ? Collector current when base open 
• I
CBO
 ? Collector current when I
E
 = 0        I
CBO
 > I
Co
 .
• V
BE,sat
  or  V
BC,sat
 ?  - 2.5 mv /
0
 C ;    V
CE,sat
 ? 
V
BE,sat
10
 = - 0.25 mv /
0
C 
• Large signal Current gain  ß =  
I
C
- I
CBo
I
B
+ I
CBo
• D.C current gain  ß
dc
 = 
I
C
I
B
 = h
FE
  
• (ß
dc
 = h
FE
 ) ˜ ß   when  I
B
 > I
CBo
• Small signal current gain ß
'
 = 
?I
C
?I
R
?
V
CE
 =  h
fe
 =  
h
FE
1-(I
CBo
+ I
B
)
?h
FE
?I
C
  
• Over drive factor =
ß
active
ß
forced
?under saturation
 ? I
C sat
 = ß
forced
 I
B sat
   
Conversion formula :- 
   CC  ? CE 
• h
ic
 = h
ie
 ;     h
rc
 = 1 ;         h
fc
 = - (1+ h
fe
) ;      h
oc
 = h
oe
 
 CB  ? CE 
• h
ib
 = 
h
ie
1+h
fe
;  h
ib
 = 
h
ie
 h
oe
1+h
fe
- h
re
 ; h
fb
 = 
-h
fe
1+h
fe
;    h
ob
 = 
h
oe
1+h
fe
CE parameters in terms of CB can be obtained by interchanging B & E . 
gradeup
gradeup
Page 3


• Energy gap
???? G/si
=1.21- 3.6 × 10
-4
.T   ev
???? G/Ge
=0.785- 2.23 × 10
-4
.T   ev
? Energy gap depending on temperature 
• E
F
 = E
C
 - KT ln?
???? ???? ???? ???? ? = E
v
 + KT ln ?
???? ???? ???? ???? ? 
• No. of electrons  n = N
c
 e
-(E
c
-E
f
)/RT
         (KT in ev) 
• No. of holes  p = N
v
 e
-(E
f
-E
v
)/RT
• Mass action law  n
p
 = n
i
2
 = N
c
N
v
 e
-EG/KT
• Drift velocity  ???? d
 = µE  (for si ???? d
 = 10
7
 cm/sec)
• Hall voltage ???? H
 = 
B.I
w
e
 . Hall coefficient  R
H
 = 1/? .            ? ? charge density = qN
0
 = ne … 
• Conductivity  s = ?µ ;  µ = sR
H
 .
• Max value of electric field @ junction E
0
 =  -
q
?
si
N
d
. n
n0
 =  -
q
?
si
 N
A
. n
p0
 . 
• Charge storage @ junction  Q
+
 = - Q
-
 = qA x
n0
N
D
 =  qA x
p0
N
A
• Diffusion current densities  J
p
 = - q D
p
 
dp
dx
J
n
 = - q D
n
 
dn
dx
• Drift current Densities  = q(p µ
p
+ nµ
n
)E
• µ
p
 , µ
n
 decrease with increasing doping concentration .
•
D
n
µ
n
= 
D
p
µ
p
 = KT/q ˜ 25 mv @ 300 K 
• Carrier concentration in N-type silicon n
n0
 = N
D
 ;  p
n0
 = n
i
2
 / N
D
• Carrier concentration in P-type silicon p
p0
 = N
A
 ;  n
p0
 = n
i
2
 / N
A
• Junction built in voltage  V
0
 = V
T
 ln ?
???? ???? ???? ???? ???? ???? 2
? 
• Width of Depletion region  W
dep
 =  x
p
 + x
n
 = ?
2e
s
q
?
1
N
A
+
1
N
D
?(V
0
+ V
R
) 
* ?
2???? ???????? ???? = 12.93???? ???????????? ???????? ?  
•
x
n
x
p
 = 
N
A
N
D
 
• Charge stored in depletion region  q
J
 = 
q.N
A
 N
D
N
A
+N
D
 . A . W
dep
  
• Depletion capacitance  C
j
 = 
e
s
A
W
dep
 ;   C
j0
 = 
e
s
A
W
dep
/ V
R
=0
C
j
 = C
j0
/? 1 +
V
R
V
0
?
m
  C
j
 = 2C
j0
  (for forward Bias) 
• Forward current  I = I
p
+ I
n
 ;       I
p
 = Aq n
i
2
D
p
L
p
N
D
 ? ???? ???? /???? ???? - 1? 
I
n
 = Aq n
i
2
 
D
n
L
n
N
A
 ? ???? ???? /???? ???? - 1?  
• Saturation Current  I
s
 = Aq n
i
2
  ?
D
p
L
p
N
D
+
D
n
L
n
N
A
? 
• Minority carrier life time  t
p
 = L
p
2
 / D
p
  ;    t
n
 = L
n
2
 / D
n
Analog Circuits 
gradeu
gradeup
• Minority carrier charge storage  Q
p
 = t
p
I
p
 ,  Q
n
 = t
p
I
n
     Q = Q
p
 + Q
n
 = t
T
I              t
T
 = mean transist time 
• Diffusion capacitance  C
d
 =  ?
???? ???? ???????? ???? ? I = t.g  ? C
d
 ? I. 
t? carrier life time ,  g = conductance = I /  ???????? ????  
• I
02
 = 2
(T
2
-T
1
)/10
 I
01
• Junction Barrier Voltage  V
j
 = V
B
 = V
r
 (open condition)
           = V
r
 - V (forward Bias) 
           =  V
r
 + V (Reverse Bias) 
• Probability of filled states above ‘E’  f(E) = 
1
1+e
(E-E
f
)/KT
  
• Drift velocity of  e
-
        ???? d
 = 10
7
 cm/sec 
• Poisson equation  
d
2
V
dx
2
 = 
-?
v
?
  = 
-nq
?
 ? 
dv
dx
 = E = 
-nqx
?
  
Transistor :- 
• I
E
 = I
DE
 + I
nE
• I
C
 = I
Co
 – a I
E
  ? Active region
• I
C
 = – a I
E
 + I
Co
 (1- e
V
C
/V
T
 )
Common Emitter :- 
• I
C
 = (1+ ß) I
Co
 + ßI
B
    ß = 
a
1-a
• I
CEO
 = 
I
Co
1-a
  ? Collector current when base open 
• I
CBO
 ? Collector current when I
E
 = 0        I
CBO
 > I
Co
 .
• V
BE,sat
  or  V
BC,sat
 ?  - 2.5 mv /
0
 C ;    V
CE,sat
 ? 
V
BE,sat
10
 = - 0.25 mv /
0
C 
• Large signal Current gain  ß =  
I
C
- I
CBo
I
B
+ I
CBo
• D.C current gain  ß
dc
 = 
I
C
I
B
 = h
FE
  
• (ß
dc
 = h
FE
 ) ˜ ß   when  I
B
 > I
CBo
• Small signal current gain ß
'
 = 
?I
C
?I
R
?
V
CE
 =  h
fe
 =  
h
FE
1-(I
CBo
+ I
B
)
?h
FE
?I
C
  
• Over drive factor =
ß
active
ß
forced
?under saturation
 ? I
C sat
 = ß
forced
 I
B sat
   
Conversion formula :- 
   CC  ? CE 
• h
ic
 = h
ie
 ;     h
rc
 = 1 ;         h
fc
 = - (1+ h
fe
) ;      h
oc
 = h
oe
 
 CB  ? CE 
• h
ib
 = 
h
ie
1+h
fe
;  h
ib
 = 
h
ie
 h
oe
1+h
fe
- h
re
 ; h
fb
 = 
-h
fe
1+h
fe
;    h
ob
 = 
h
oe
1+h
fe
CE parameters in terms of CB can be obtained by interchanging B & E . 
gradeup
gradeup
• A
I
 =
-h
f
1+h
0
Z
L
 Z
i
 = h
i
 + h
r
 A
I
Z
L
          A
vs
 = 
A
v
.Z
i
Z
i
+R
s
Z
i
+R
s
 = 
A
I
.Z
L
 = 
A
I
s
.Z
L
R
s
A
V
 = 
A
I
  Z
L
Z
i
Y
0
 = h
o
 - 
h
f
 h
r
h
i
+ R
s
A
Is
 = 
A
v
.R
s
Z
i
+R
s
  = 
A
vs
.R
s
Z
L
  
Choice of Transistor Configuration :- 
• For intermediate stages CC can’t be used as  A
V
 < 1
• CE can be used as intermediate stage
• CC can be used as o/p stage as it has low o/p impedance
• CC/CB can be used as i/p stage because of i/p considerations.
Stability & Biasing :- ( Should be as min as possible) 
• For  S = 
?I
C
?I
Co
?
V
B0,ß
    S
'
 = 
?I
C
?V
BE
?
I
C0,ß
          S
''
 = 
?I
C
?ß
?
V
BE,I
Co
 ?I
C
 = S. ?I
Co
  + S
'
 ?V
BE
 + S
''
 ?ß  
• For fixed bias  S =
1+ß
1-ß
dI
B
dI
C
  = 1 + ß  
• Collector to Base bias  S = 
1+ß
1+ß
R
C
R
C
+R
B
           0 < s < 1+ ß  = 
1+ß
1+ß?
R
C
+ R
E
R
C
+ R
E
+ R
B
?
• Self bias  S =  
1+ß
1+ß
R
E
R
E
+R
th
  ˜ 1+ 
R
th
R
e
          ßR
E
  > 10 R
2
 
• R
1
 = 
V
cc
 R
th
V
th
;  R
2
 = 
V
cc
 R
th
V
cc
-V
th
• For thermal stability [ V
cc
 - 2I
c
 (R
C
 + R
E
)] [ 0.07 I
co
 . S]  <  1/?  ; V
CE
 < 
V
CC
2
Hybrid –pi(p)- Model :- 
  g
m
 = |I
C
 | / V
T
   
 r
b
'
e
  =  h
fe
 / g
m
         
r
b
'
b
 = h
ie
 - r
b
'
e
r
b
'
c
 = r
b
'
e
 / h
re
        
g
ce
 = h
oe
 - (1+ h
fe
 ) g
b
'
c
    
Specifications of An amplifier :- 
gradeup
gradeup
Read More
27 docs

Top Courses for Electronics and Communication Engineering (ECE)

27 docs
Download as PDF
Explore Courses for Electronics and Communication Engineering (ECE) exam

Top Courses for Electronics and Communication Engineering (ECE)

Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Related Searches

Summary

,

Free

,

Objective type Questions

,

pdf

,

Short Notes: Analog Circuits | Short Notes for Electronics and Communication - Electronics and Communication Engineering (ECE)

,

mock tests for examination

,

Semester Notes

,

Short Notes: Analog Circuits | Short Notes for Electronics and Communication - Electronics and Communication Engineering (ECE)

,

Sample Paper

,

Important questions

,

video lectures

,

Previous Year Questions with Solutions

,

shortcuts and tricks

,

study material

,

Viva Questions

,

Short Notes: Analog Circuits | Short Notes for Electronics and Communication - Electronics and Communication Engineering (ECE)

,

practice quizzes

,

ppt

,

Exam

,

Extra Questions

,

past year papers

,

MCQs

;