Embed Size (px)
Citation preview
Frequency Response
Common Base &
Common Collector
Common Base Circuit
Low Frequency Equivalent Circuit
Low Frequency Equivalent Circuit
0 0)(
0)( 1
e
z
IoncesV
sVFor
Short Circuit Time Constant :LFRZero Freq ωZ1
inS
ins
ininseS
inssig
inseS
sige
esig
e
sig
sig
sig
o
RCZRsC
RRsCrR
RsCV
RCrR
VI
sI
sVo
sV
sI
sV
sV
sV
sV
1101
011'
11'
1||
'
'
)(
)(
)('
)(
)(
)('
)(
)(
)(
)(
)('
)(
)(
)('
)(
)(
sI
sVo
sV
sI
sV
sV
sV
sV
esig
e
sig
sig
sig
o
ins
e
z
RC
IoncesV
sVFor
||
0 0)(
0)( 1
insz
insins
inins
RC
RsCRsC
RRC
1
011
||
1
Short Circuit Time Constant :LFRZero Freq ωZ1
SEeeq
seq
RRrRRR
is for CR
||1|||| 21 eqsp RC
11
Short Circuit Time Constant :LFRPole Freq ωp1 - Req for Cs
Short Circuit Time Constant :LFR Zero Freq ωZ2
01
02
s)ures Vo(cted ens open cCcz
Short Circuit Time Constant :LFR Pole Freq ωp2 Req for CC1
LCeq
Ceq
RRR
is for CR
2
eqCp RC 2
2
1
Short Circuit Time Constant :LFRZero Frequency : ωZCc2
01
02
(s)Voures Vcted ens open cCc osig
z
Short Circuit Time Constant :LFRωpCc2 Req for CC1
eESeq
Ceq
rRRR
is for CR
||
1
eqCp RC 1
3
1
High Frequency Equivalent Circuit
Open Circuit Time Constant : HFR
LCeq RRR ||eq
p
z
RC
1
3
3
3
3
01
0)(
z
z
sCs
sVoFor
is for CReq
Open Circuit Time Constant : HFR
seeq
eq
RrR
is for CR
'||
eqp
z
RC
1
3
3
Low Frequency Response : CC Configuration
β =120
DC Anaysis : CC Configuration
β =120ModeActiveVV
VRIVVV
mAR
R
VVI
BC
EEBC
BE
BECCE
V 4.0
3,5
595.0
1
krr
I
Vr
e
E
Te
084.51
42
Mid-band Gain AM
Configuration is CC so ‘T’ Model
VVv
v
kRRrRR
RR
R
RRr
RR
RR
R
RRr
RRrg
v
v
RR
R
RRr
rRRg
v
v
v
v
v
v
v
v
sig
o
LEeBin
sigin
in
LEe
LE
sigin
in
LEe
LEem
sig
o
sigin
in
LEe
eLEm
sig
i
i
be
be
o
sig
o
/922.0
4.147||1||
||
||
||
||
||
||
Low Frequency Response : Cc1
(β+1)IB
A B
kRrRRR
RRR
LeBsigeq
insigeq
4.157)')(1(||1
1
3111
1 104.157
11
ceqcp CRC
IB
Low Frequency Response : Cc2
kRR
rRRR sigBeELeq 72.5
)1(
||||2
3222
2 1072.5
11
ceqcp CRC
I
I/β+1
Iβ/β+1
Designing of Coupling Capacitors
Design the coupling capacitors so that a dominant low frequency pole at 10 Hz is obtained.
Design so that the contribution of the capacitors are in the ratio of 10:1 and the total capacitance is minimized
FCC
antpoledof cC
L 06.31072.5
1min2
11
1023
2
FCC
poleotherf cC
L 11.11042.157
1 2
11
113
1
LLL fHzf 210
Standard Capacitors
Design requires CC1 = 1.11μF & CC2 =3.06 μF
Standard Capacitor Available commercially are CC1 = 1.0μF & CC2 =3.3 μF
So selecting Standard capacitorDominant Low frequency pole @ fL=9.44 Hz
Low frequency response : Cc1 & Cc2
(a) Mid-band Gain
(b) High Frequency response
Common Collector Configuration
Mid-band Gain
Midband gain : Solution No 1
vi
vbe
+
-
sig
i
i
be
be
o
sig
o
v
v
v
v
v
v
v
v
LEeBin
sigin
in
LEe
LE
sig
o
sigin
in
LEe
eLE
m
sig
o
RRrRR
RR
R
RRr
RR
v
v
RR
R
RRr
rRR
g
v
v
||1||
||
||
||||
Midband gain : Solution No 2
vi
vbe
+
-
sig
i
i
o
sig
o
v
v
v
v
v
v
LEeBin
sigin
in
LEe
LE
sig
o
RRrRR
RR
R
RRr
RR
v
v
||1||
||
||
Midband gain : Solution No 3
sigBsig
Bsig
Bsigsig
VRR
RV
RRR
'
||'ib
ßib
Vo
ib
ßib
Vo
Midband gain : Solution No 3
Lesig
sigb
Lesigbsig
Lebsigbsig
RrR
vi
RrRiv
RriRiv
'1'
'
'1''
'1''
Lbo Riv '1
sigB
B
Lesig
L
sig
o
RR
R
RrR
R
v
v
'1'
'1
LEL
sigBsig
Bsig
Bsigsig
RRR
VRR
RV
RRR
||'
'
||'
High Frequency Response
High Frequency Response
LEL
sigBsig
Bsig
Bsigsig
RRR
VRR
RV
RRR
||'
'
||'
Open Circuit Time Constant
Vb
Is
Vb
Is
Open Circuit Time Constant :CReq
IbI1
LsmE RIVgV '1
LsmsEsb RIVgVVVV '1 LLmssig RIRgVRI ''1' 11
LmsLsig RgVRRI '1''1 Z
Rg
RR
I
V
Lm
Lsigs
'1
''
1
r
VI
r
VIIII s
se
ssbs
11
rZ
rZVI
r
VII
Z
Vss
ss
s1
Lm
Lsig
s
seq Rg
RRrZr
I
VR
C '1
''||||
gmVs-I1
Open Circuit Time Constant :ReqCπ
Ib
I1
gmvs
Lm
Lsig
s
seq Rg
RRrZr
I
VR
C '1
''||||
sLsmsig VRVgIRI '' 11
sLmLsig VRgRRI '1''1
Z
Rg
RR
I
V
Lm
Lsigs
'1
''
1
r
VI
r
VIIII s
se
ssbs
11
rZ
rZVI
r
VII
Z
Vss
ss
s1
Open Circuit Time Constant :ReqCπ
Ib
I1
(gmVs-I1)
ßIb
LsmE RIVgV '1
LsmsEsb RIVgVVVV '1 LLmssig RIRgVRI ''1' 11
LmsLsig RgVRRI '1''1 Z
Rg
RR
I
V
Lm
Lsigs
'1
''
1
r
VIIII s
sbs 1
rZ
rZVI
r
VII
Z
Vss
ss
s1
Lm
Lsig
s
seq Rg
RRrZr
I
VR
C '1
''||||
Is
Open Circuit Time Constant :CReq
I1
ßIb
ss
sbs Ir
VIrIIrIV
11
rZ
rZVII
r
VI
Z
Vsss
ss1
Lm
Lsig
s
seq Rg
RRrZr
I
VR
C '1
''||||
Is 0'' 11 Lsmssig RVgIVRI
sLmLsig VRgRRI '1''1
Z
Rg
RR
I
V
Lm
Lsigs
'1
''
1
Ib
High Frequency Response :Req Cμ
IS
IbI1
bS III 1
Le
s
sig
sS Rr
V
R
VI
'1'
LesigS
seqC RrR
I
VR '1||'
βIb
(β+1)Ib
High Frequency Response :ReqCµ
LebLeBbs
sigsigs
RrIRrIIV
RIV
'1'
'
Le
s
sig
sS Rr
V
R
VI
'1'
LesigS
seqC RrR
I
VR '1||'
bsigs III
