Chapter 10 Transistor amplifier design 509/icerik... · 2016. 11. 28. · > b À 3 ± Chapter 10...
Transcript of Chapter 10 Transistor amplifier design 509/icerik... · 2016. 11. 28. · > b À 3 ± Chapter 10...
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Chapter 10 Transistor amplifier design
10.1 Stability considerations
unconditionally stable, conditionally stable, stability factor, source stability circle,
load stability circle
10.2 Amplifier design for maximum gain
unilateral case, bilateral case, simultaneously conjugate match, unilateral figure
of merit
10.3 Constant gain circles
unilateral case, bilateral case
10.4 Constant noise figure circles
10.5 Broadband amplifiers
negative feedback amplifier, balanced amplifier, traveling wave amplifier
10.6 Small signal equivalent circuit models of transistors
BJT, MESFET
10.7 DC bias circuits for transistors
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10.1 Stability considerations
Basics
1. Unconditionally stable
1
12
1
11
11
1,1allfor
12212211
1221
22
22
2
11
11
122122out
22
122111in
Ls
SSSS
SS
SSk
S
SSS
S
SSS
s
s
L
L
2. Conditionally stable: there exists some s and L, such that one or both of these
conditions violated.
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Discussion
1. Stability circles
22
11
2112
22
11
*
2211s
s
11
211222out
22
22
2112
22
22
*
1122L
L
22
122111in
,)(
with plane-in
circlestability11
,)(
with plane-in
circlestability11
S
SSr
S
SSC
rCloadS
SSS
S
SSr
S
SSC
rCloadS
SSS
ss
ss
s
s
LL
LL
L
L
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� �
2. If L=0 in=S11, the center of Smith chart represent a stable point if S11
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4. Ex.10.1 A transistor has S11=0.894 -60.6 , S12=0.02 62.4, S21=3.122 123.6 ,
S22=0.781 -27.6 at 2GHz
2.0,7.4636.1
5.0,7.4636.1
1607.02
1,16964.0
1221
22
22
2
11
12212211
Ls
LL
rC
rC
SS
SSkSSSS
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� � � �
10.2 Amplifier design for maximum gain
Basics
1.Unilateral case: S12=0
stability condition: S11
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2. Bilateral case (simultaneously conjugate match)
*
11222
*
22111
22
11
2
222
22
22
2
111
1
2
1
2
11
11
122122out
*
L
2
2
2
2
22
22
122111in
*
s
12
212
12
21
2
s11
2
2
2122
L22
2
2
212
*
Lo
*
in
,
1,1
2
4
1
2
4
1
1kasgainstablemaximum:),1(
1
1
1
1
1
1
1
1
,smatchconjugateuslysimultaneooutputandinput
1,1
SSCSSC
SSBSSB
C
CBB
S
SSS
C
CBB
S
SSS
S
SGKK
S
S
SS
SSGG
Kif
Ms
s
s
ML
L
L
MSG
s
L
L
s
TMaxT
ut
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� � � �
3. Unilateral figure of merit
)1)(1(
)1(
1
)1(
1
2
22
2
11
22122111
22
SS
SSSSU
UG
G
U U
T
Discussion
1. Linear amplifier design procedure
(1) if | 1, use input and output simultaneously conjugate matches for GTmax
(2) if K
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2. Ex.10.2, A transistor has (Zo=50 ), S11=0.606 -155 , S12=0, S21=6 180 ,
S22=0.48 -20 at 1GHz design an amplifier to give GTUmax.
dB
SS
SG
SS
SS
TU
Ls
69.189.733.13658.1
48.01
16
606.01
1
1
1
1
1
2048.0,155606.0
148.0,1606.0
2
2
22
22
2
212
11
max
*
22
*
11
2211
1: y=j1.7, or z=-j0.45
2: z=j0.2
3: z=-j1.38, or y=j0.48
4: y=-j0.16
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$ % & $ %
3. Ex.10.2 A transistor has (Zo=50 ), S11=0.614 -167.4 , S12=0.046 65 ,
S21=2.187 32.4 , S22=0.716 -83 at 6GHz design an amplifier to give Gtmax
| 1
dBKKS
SG
C
CBB
C
CBB
TMax
Ms
ML
58.14728.28)1(
48.849011.02
4
4.1678673.02
4
2
12
21
1
2
1
2
11*
Lout
2
2
2
2
22*
sin
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' ( ) ' '
1: MS=0.8673 169.76
2: y=-j2.7
3: ML=0.9011 84.48
4: z=j3.4
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* + , * -
4. Ex.10.4 transistor A: S11=0.45 150 , S12=0.01 -10 , S21=2.05 10 , S22=0.4
-10 transistor B: S11=0.641 -171.3 , S12=0.057 16.3 , S21=2.058 28.5 ,
S22=0.572 -95.7 compare their Us
dBG
GdB
dBG
GdB
G
G
G
G
UG
G
U
U
U
SS
SSSSU
B
U
T
A
U
T
B
U
T
A
U
T
U
T
A
9976.08948.0
0238.0476.0
2582.18238.0
0055.19891.0
)1(
1
)1(
1
1085.0
00551.0
)1)(1(
22
2
22
2
11
22122111
B
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. / 0 . 1
10.3 Constant gain circles
Basics
1. Unilateral case (S12=0)
2
22
2
22
2
22
*
22
LL
max
2
11
2
11
2
11
*
11
ss
max
2
22
max2
22
2
2
11
max2
11
2
02
22
2
2
212
11
2
)1(1
)1(1,
)1(1
incirclesgainconstant
)1(1
)1(1,
)1(1
incirclesgainconstant
1
1,
1
1,
1
1,
1
1
1
1
1
1
Sg
SgR
Sg
Sgd
RdplaneG
Gg
Sgs
SgsRs
Sgs
Sgds
RsdsplaneG
Ggs
SG
SG
SG
SG
GGGS
SS
G
L
L
L
L
LL
LL
L
LL
s
s
s
L
L
L
Ls
s
s
s
Ls
L
L
s
s
TU
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3 4 5 3 6
2. Bilateral case (S12 0)
(1) Unconditionally stable case, use GP or GA
max
2
12
21
max
2
2112
max
*
1122222
22
22
21122112
22
22
*
2
LL2
L11
2
L22
2
2
21
22
11
22
1221112
L22
2
2
212
)1(
)1(1
,)(1
21,
)(1
incirclesgainconstant1
1
11,
1
1
1
1
TPP
PP
P
P
PP
P
P
PP
PP
L
P
PP
L
L
L
Lim
L
im
P
GKKS
SGG
KKSS
gg
R
SSCSg
gSSgSSKR
Sg
Ccc
RcplaneSS
g
gSG
S
S
S
SSS
SSG
-
7 8 9 7 :max
2
12
21
max
2
2112
max
*
2211122
11
22
21122112
22
11
*
1
ss2
s22
2
s11
2
2
21
11
22
11
1221222
2
212
S11
2
)1(
)1(1
,)(1
21,
)(1
incirclesgainconstant1
1
11,
1
1
1
1
TAA
AA
s
A
AA
s
A
As
ss
S
A
AP
s
s
s
sout
out
S
A
GKKS
SGG
KKSS
gg
R
SSCSg
gSSgSSKR
Sg
Cgc
RcplaneSS
g
gSG
S
S
S
SSSS
SG
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; < = ; >
(2) Potentially unstable case
use GP to plot constant gain circles in L-plane and plot load stability circles
properly select L, calculate s= in
use GA to plot constant gain circles in s-plane and plot source stability circles
properly select s, calculate L= out
Discussion
1. Ex. 10.5 A MESFET with S-parameters (Zo=50 )
S11 S21 S12 S22
3GHz 0.8 -90 2.8 100 0 0.66 -50
4GHz 0.75 -120 2.5 80 0 0.6 -70
5GHz 0.71 -140 2.3 60 0 0.68 -85
plot constant gain circles @4GHz for GL=0, 1dB, and Gs=2, 3dB design an
amplifier of 11dB gain
dBGdBSG
dBS
GdBS
G
GGGS
SS
G
TU
Ls
Ls
L
L
s
s
TU
47.1392.196.759.3,96.725.6
92.15625.11
1,59.3228.2
1
1GHz,4@
1
1
1
1
max
2
210
2
22
max2
11
max
02
22
2
2
212
11
2
-
? @ A ? B
chose GTU(4GHz) 11dB=2dB+8dB+1dB to design the circuit
GTU(3GHz)=7.3GTU(5GHz)=6.96dB
44.0
303.0,
7064.0
7052.0
64.0
8064.0
10
26.11
294.0
166.0,
120627.0
120706.0
691.0
785.0
58.12
23
LLLL
s
RdgdB
dBG
RdsgsdB
dBGs
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C D E C F
2. Ex. 10.6 A GaAs FET with S-parameters (Zo=50 , 1GHz) S11=2.27 -120 , S21=4
50 , S12=0, S22=0.6 -80
(1) calculate Zin, plot unstable region in s-plane
(2) plot constant gain circles for Gs=3, 5dB
(3) find Zs for Gs=3dB with maximum degree of stable, determine ZL to give maximum
GL, then design the amplifier
(4) calculate GTU
unstablebe to5.24
235.240
012027.2)1( 11
Rs
jZinZZin
ZZinS in
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G H I G J
(2)
dBGS
G
jZSFor
jZssA
TULMAX
LL
175056.142,56.11
1
5.5127806.0:CselectGL,maximum
25507624.0:
Rspossiblemaximumagivetofor ZsASelect(3)
2
2
22
*
22
2698.0
2174.0,
1204.0
12045.0
3.8
13.13
23
16.35sRdsgs
dB
dBGs
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K L M N L
3. Ex. 10.7 A GaAs FET with S-parameters (Zo=50 , 6GHz) S11=0.641 -171.3 ,
S21=2.058 28.5 , S12=0.057 16.3 ,S22=0.572 -95.7 design an amplifier to
give GP=9dB
6.17563.0:6.17563.05036.0:Cselect
43.0,1045.0
planeincirclesgainconstant9
38.11)1(3.01.5K
sL
LL
2
12
21
A
Rc
RcdBG
dBKKS
SGG
in
pp
ppP
PMaxP
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O P Q R O
4. Ex. 10.8 A GaAs FET with S-parameters (Zo=50 , 8GHz) S11=0.5 -180 ,
S21=2.5 70 , S12=0.08 30 , S22=0.8 -100 design an amplifier to give
GP=10dB
3.17952.0:3.17952.0971.0:Cselect
4733.0,2.9757.0
planeincirclesgainconstant10
3388.0,9717.1Ccirclestabilityload
998.0,6.17067.1Cscirclestabilitysource2228.0.3990K
sL
LL
L
A
Rc
RcdBG
r
rs
in
pp
ppP
L
-
S T U V V
5. Ex. 10.9 A BJT with S-parameters (Zo=50 , 750MHz) S11=0.277 - 59 , S21=1.92
64 , S12=0.078 93 , S22=0.848 -31 design an amplifier to give GTmax
6. Ex. 10.10 use the BJT in Ex.10.9 design an amplifier to give GP=10dB,
determine Gs, GL for GPmax
°3.8530.9511=?3510.7298=
matchconjugateuslysimultaneo3242.0,0325.1|G|
MLMS
Ss
LL
s
L
LL
1357298.0
84.339511.08.12
45.563455.0:
4.563455.03456.0:Cselect
2142.0,8.3378.0
planeincirclesgainconstant10
M
MMAXP
in
pp
ppP
dBG
A
Rc
RcdBG
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W X Y Z [
10.4 Constant noise figure circles
Basics
amplifier port - two a For
1
)1(,
1
circlefigurenoiseconstant
parameterfigurenoise:1/41
N
r transistoofresistancenoiseequivalent,,:parameternoise
1)1(
4
2
2
0
min
2
2
min
22
2
0
min
2
min
N
NNNR
NC
RC
ZR
FF
RYF
Z
RFYY
G
RFF
opt
NF
opt
NF
NFNFs
opt
ns
opts
nopt
opts
optsnopts
s
n
-
\ ] ^ _ `
Discussion
1. Ex. 10.11 A BJT with S-parameters (Zo=50 , 1GHz) S11=0.707 -155 , S21=5
180 , S12=0, S22=0.51 -20 , Fmin=3dB, Rn=4 , opt= 0.45 180 design an
amplifier to give GT=16dB, F
-
a b c d e
2. Ex. 10.12 A GaAs FET with S-parameters (Zo=50 , 4GHz) S11=0.6 -60 ,
S21=1.9 81 , S12=0.05 26 , S22=0.5 -60 , Fmin=1.6dB, Rn=20 , opt= =0.62
100 (1) assume S12=0, design an amplifier to give GTUmax, F
-
f g h i j
8.67504.08.67504.090535.0
234.0,7.64527.08G
planeincirclesgainconstantGuse)2(
A
ssA
Louts
ss
ss
select
RcdB
Rc
3. Low noise amplifier design procedure:
if unconditionally stable, use GA constant gain circles and constant noise figure
circles to determine s , and L= *out.
if potentially unstable, consider source and load stability circles in addition.
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k l m n op , 1GHz) S11=0.6 -130 , S21=7.12
86 , S12=0.039 35 , S22=0.5 -38 , Fmin=1.3dB, Rn=8 , opt= =0.06 49
design an amplifier to give 16dB power gain, F
-
q r s t u
10.5 Broadband amplifiers
Basics
1. Negative feedback amplifier
''
1'),1('
)1(1
1
1
1
00
0
000
0
0
0
0
0
cc
cc
c
V
v
v
i
V
fAfA
A
AAAff
Af
fj
A
A
G
fc
fj
AAv
A
A
V
VG
-
v w x y z
2. Balanced amplifier
{ hybrids and amplifier gain.
-
| } ~ }
2. Traveling wave amplifier (distributed amplifier) TEM line “extreme wide operation
bandwidth”
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10.6 Small-signal equivalent circuit models of transistor
Basics
1. BJT
-
2. MESFET
powergate
fgate
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10.7 DC bias circuits for transistors
Discussion
1. Resistive bias with voltage feedback for BJT,inchanges tosensitivelesshave
1,
1
,
,
BEE
BBEcc
B
BEccE
CBEE
BEBBE
VIto
RRcVV
RRc
VVI
IIIIIc
VRIRcIVcc
-
2. Bias circuit with emitter bypassed resistor for BJT
inth
cc
cECBth
BEE
thEBEth
thE
BEccE
BEEEth
EEBEBthTh
THCCTH
RR
V
VVV
VIto
RRVV
RR
VVI
VIRR
RIVIRV
RR
RRRV
RR
RV
20%~15%Vthusually
swingoutputitedlim,
,inchanges tosensitivelesshave
1,
1
,)1
(
,21
21
21
2
-
3. Unipolar bias circuits for MESFET