Philips Semiconductors
SA5205A
Wide-band high-frequency amplifier
Product specification
Replaces data of February 24, 1992
1997 Nov 07
INTEGRATED CIRCUITS
IC17 Data Handbook
Philips Semiconductors
Product specification
SA5205A
Wide-band high-frequency amplifier
2
1997 Nov 07
853-1598 18662
DESCRIPTION
The SA5205A family of wideband amplifiers replace the SA5205
family. The ‘A’ parts are fabricated on a rugged 2
µ
m bipolar process
featuring excellent statistical process control. Electrical
performance is nominally identical to the original parts.
The SA5205A is a high-frequency amplifier with a fixed insertion
gain of 20dB. The SA5205A operates with a single supply of 6V, and
only draws 24mA of supply current, which is much less than
comparable hybrid parts. The noise figure is 4.8dB in a 75
Ω
system
and 6dB in a 50
Ω
system.
Until now, most RF or high-frequency designers had to settle for
discrete or hybrid solutions to their amplification problems. Most of
these solutions required trade-offs that the designer had to accept in
order to use high-frequency gain stages. These include high-power
consumption, large component count, transformers, large packages
with heat sinks, and high part cost. The SA5205A solves these
problems by incorporating a wide-band amplifier on a single
monolithic chip.
The part is well matched to 50 or 75
Ω
input and output impedances.
The Standing Wave Ratios in 50 and 75
Ω
systems do not exceed
1.5 on either the input or output from DC to the -3dB bandwidth limit.
Since the part is a small monolithic IC die, problems such as stray
capacitance are minimized. The die size is small enough to fit into a
very cost-effective 8-pin small-outline (SO) package to further
reduce parasitic effects.
No external components are needed other than AC coupling
capacitors because the SA5205A is internally compensated and
matched to 50 and 75
Ω
. The amplifier has very good distortion
specifications, with second and third-order intermodulation
intercepts of +24dBm and +17dBm respectively at 100MHz.
The device is ideally suited for 75
Ω
cable television applications
such as decoder boxes, satellite receiver/decoders, and front-end
amplifiers for TV receivers. It is also useful for amplified splitters and
antenna amplifiers.
The part is matched well for 50
Ω
test equipment such as signal
generators, oscilloscopes, frequency counters and all kinds of signal
analyzers. Other applications at 50
Ω
include mobile radio, CB radio
and data/video transmission in fiber optics, as well as broad-band
LANs and telecom systems. A gain greater than 20dB can be
achieved by cascading additional SA5205As in series as required,
without any degradation in amplifier stability.
PIN CONFIGURATIONS
8
7
6
5
4
3
2
1
VCC
VIN
GND
GND
VCC
VOUT
GND
GND
D Packages
TOP VIEW
20dB
SR00215
Figure 1. Pin Configuration
FEATURES
•
600MHz bandwidth
•
20dB insertion gain
•
4.8dB (6dB) noise figure ZO=75
Ω
(ZO=50
Ω
)
•
No external components required
•
Input and output impedances matched to 50/75
Ω
systems
•
2000V ESD protection
APPLICATIONS
•
75
Ω
cable TV decoder boxes
•
Antenna amplifiers
•
Amplified splitters
•
Signal generators
•
Frequency counters
•
Oscilloscopes
•
Signal analyzers
•
Broad-band LANs
•
Fiber-optics
•
Modems
•
Mobile radio
•
Security systems
•
Telecommunications
ORDERING INFORMATION
DESCRIPTION
TEMPERATURE RANGE
ORDER CODE
DWG #
8-Pin Plastic Small Outline (SO) package
-40 to +85
°
C
SA5205AD
SOT96-1
Philips Semiconductors
Product specification
SA5205A
Wide-band high-frequency amplifier
1997 Nov 07
3
EQUIVALENT SCHEMATIC
VCC
VOUT
VIN
R1
Q3
Q1
Q4
RF1
RE1
RF2
RE2
Q2
R2
Q6
R3
Q5
SR00216
Figure 2. Equivalent Schematic
ABSOLUTE MAXIMUM RATINGS
SYMBOL
PARAMETER
RATING
UNIT
V
CC
Supply voltage
9
V
V
AC
AC input voltage
5
V
P-P
T
A
Operating ambient temperature range
SA grade
-40 to +85
°
C
P
DMAX
Maximum power dissipation,
T
A
=25
°
C (still-air)
1, 2
D package
780
mW
NOTES:
1. Derate above 25
°
C, at the following rates:
D package at 6.2mW/
°
C
2. See “Power Dissipation Considerations” section.
Philips Semiconductors
Product specification
SA5205A
Wide-band high-frequency amplifier
1997 Nov 07
4
DC ELECTRICAL CHARACTERISTICS
V
CC
=6V, Z
S
=Z
L
=Z
O
=50
Ω
and T
A
=25
°
C in all packages, unless otherwise specified.
SYMBOL
PARAMETER
TEST CONDITIONS
SA5205A
UNIT
SYMBOL
PARAMETER
TEST CONDITIONS
Min
Typ
Max
UNIT
V
CC
Operating supply voltage range
Over temperature
5
5
8
8
V
V
I
CC
Supply current
Over temperature
20
19
25
25
32
33
mA
mA
S21
Insertion gain
f=100MHz
Over temperature
17
16.5
19
21
21.5
dB
S11
Input return loss
f=100MHz
25
dB
S11
Input return loss
DC - f
MAX
12
dB
S22
Output return loss
f=100MHz
27
dB
S22
Output return loss
DC - f
MAX
12
dB
S12
Isolation
f=100MHz
-25
dB
S12
Isolation
DC - f
MAX
-18
dB
t
R
Rise time
500
ps
t
P
Propagation delay
500
ps
BW
Bandwidth
±
0.5dB
450
MHz
f
MAX
Bandwidth
-3dB
550
MHz
Noise figure (75
Ω
)
f=100MHz
4.8
dB
Noise figure (50
Ω
)
f=100MHz
6.0
dB
Saturated output power
f=100MHz
+7.0
dBm
1dB gain compression
f=100MHz
+4.0
dBm
Third-order intermodulation
intercept (output)
f=100MHz
+17
dBm
Second-order intermodulation
intercept (output)
f=100MHz
+24
dBm
Philips Semiconductors
Product specification
SA5205A
Wide-band high-frequency amplifier
1997 Nov 07
5
35
34
32
30
28
26
24
22
20
18
16
5
5.5
6
6.5
7
7.5
8
SUPPLY VOLTAGE—V
SUPPL
Y
CURRENT—mA
TA = 25
o
C
SR00217
Figure 3. Supply Current vs Supply Voltage
NOISE FIGURE—dBm
vcc = 6v
vcc = 8v
vcc = 7v
vcc = 5v
9
8
7
6
5
ZO = 50
Ω
TA = 25
o
C
FREQUENCY—MHz
101
2
4
6
8
2
4
6
8
102
103
SR00219
Figure 4. Noise Figure vs Frequency
INSERTION GAIN—dB
25
20
15
10
101
2
4
6
8
2
4
6
8
102
103
vcc = 8v
vcc = 7v
vcc = 6v
vcc = 5v
FREQUENCY—MHz
ZO = 50
Ω
TA = 25
o
C
SR00221
Figure 5. Insertion Gain vs Frequency (S
21
)
INSERTION GAIN—dB
TA = 55
o
C
TA = 25
o
C
TA = 85
o
C
TA = 125
o
C
VCC = 8V
ZO = 50
Ω
25
20
15
10
101
2
4
6
8
2
4
6
8
102
103
FREQUENCY—MHz
SR00223
Figure 6. Insertion Gain vs Frequency (S
21
)
OUTPUT LEVEL—dBm
FREQUENCY—MHz
ZO = 50
Ω
TA = 25
o
C
VCC = 8V
VCC = 7V
VCC = 6V
VCC = 5V
2
3
4
5
6
7
8
9
10
11
1
0
–1
–2
–3
–4
–5
–6
101
2
4
6
8
2
4
6
8
102
103
SR00218
Figure 7. Saturated Output Power vs Frequency
OUTPUT LEVEL—dBm
VCC = 8V
VCC = 7V
VCC = 6V
VCC = 5V
ZO = 50
Ω
TA = 25
o
C
10
9
8
7
6
5
4
3
2
1
0
–1
–2
–3
–4
–5
–6
FREQUENCY—MHz
101
2
4
6
8
2
4
6
8
102
103
SR00220
Figure 8. 1dB Gain Compression vs Frequency
40
35
30
25
20
15
10
4
5
6
7
8
9
10
POWER SUPPLY VOLTAGE—V
SECOND–ORDER INTERCEPT—dBM
ZO = 50
Ω
TA = 25
o
C
SR00222
Figure 9. Second-Order Output Intercept vs Supply Voltage
30
25
20
15
10
5
4
5
6
7
8
9
10
POWER SUPPLY VOLTAGE—V
THIRD–ORDER INTERCEPT—dBm
ZO = 50
Ω
TA = 25
o
C
SR00224
Figure 10. Third-Order Intercept vs Supply Voltage
Philips Semiconductors
Product specification
SA5205A
Wide-band high-frequency amplifier
1997 Nov 07
6
INPUT VSWR
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
10
1
2
4
6
8 10
2
2
4
6
8 10
3
FREQUENCY—MHz
TA = 25
o
C
VCC = 6V
ZO = 75
Ω
ZO = 50
Ω
.
SR00225
Figure 11. Input VSWR vs Frequency
INPUT VSWR
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
10
1
2
4
6
8 10
2
2
4
6
8 10
3
FREQUENCY—MHz
Tamb = 25
o
C
VCC = 6V
ZO = 75
Ω
ZO = 50
Ω
SR00227
Figure 12. Output VSWR vs Frequency
40
35
30
25
20
15
10
101
2
4
6
8 102
2
4
6 8 103
OUTPUT
INPUT
FREQUENCY—MHz
VCC = 6V
ZO = 50
Ω
TA = 25
o
C
INPUT RETURN LOSS—dB
OUTPUT RETURN LOSS—dB
SR00229
Figure 13. Input (S
11
) and Output (S
22
) Return Loss vs
Frequency
VCC = 6V
ZO = 50
Ω
TA = 25
o
C
10
–15
–20
–25
–30
ISOLA
TION—dB
FREQUENCY—MHz
101
2
4
6
8 102
2
4
6
8 103
SR00226
Figure 14. Isolation vs Frequency (S
12
)
ISOLA
TION GAIN—dB
15
10
25
20
ZO = 75
Ω
TA = 25
o
C
vcc = 8v
vcc = 7v
vcc = 6v
vcc = 5v
FREQUENCY—MHz
101
2
4
6 8
2
4
6
8
102
103
SR00228
Figure 15. Insertion Gain vs Frequency (S
21
)
INSERTION GAIN—dB
25
20
15
10
ZO = 75
Ω
VCC = 6V
TA = –55
o
C
TA = 25
o
C
TA = 85
o
C
TA = 125
o
C
FREQUENCY—MHz
101
2
4
6
8
2
4
6
8
102
103
SR00230
Figure 16. Insertion Gain vs Frequency (S
21
)
Philips Semiconductors
Product specification
SA5205A
Wide-band high-frequency amplifier
1997 Nov 07
7
THEORY OF OPERATION
The design is based on the use of multiple feedback loops to
provide wide-band gain together with good noise figure and terminal
impedance matches. Referring to the circuit schematic in Figure 17,
the gain is set primarily by the equation:
V
OUT
V
IN
+
R
F1
)
R
E1
R
E1
(1)
which is series-shunt feedback. There is also shunt-series feedback
due to R
F2
and R
E2
which aids in producing wideband terminal
impedances without the need for low value input shunting resistors
that would degrade the noise figure. For optimum noise
performance, R
E1
and the base resistance of Q
1
are kept as low as
possible while R
F2
is maximized.
The noise figure is given by the following equation:
NF =
10 log
1
)
r
b
)
R
E1
)
KT
2ql
C1
R
O
dB
(2)
where I
C1
=5.5mA, R
E1
=12
Ω
, r
b
=130
Ω
, KT/q=26mV at 25
°
C and
R
0
=50 for a 50
Ω
system and 75 for a 75
Ω
system.
The DC input voltage level V
IN
can be determined by the equation:
V
IN
=V
BE1
+(I
C1
+I
C3
) R
E1
where R
E1
=12
Ω
, V
BE
=0.8V, I
C1
=5mA and I
C3
=7mA (currents rated
at V
CC
=6V).
Under the above conditions, V
IN
is approximately equal to 1V.
Level shifting is achieved by emitter-follower Q
3
and diode Q
4
which
provide shunt feedback to the emitter of Q
1
via R
F1
. The use of an
emitter-follower buffer in this feedback loop essentially eliminates
problems of shunt feedback loading on the output. The value of
R
F1
=140
Ω
is chosen to give the desired nominal gain. The DC
output voltage V
OUT
can be determined by:
V
OUT
=V
CC
-(I
C2
+I
C6
)R2,(4)
where V
CC
=6V, R
2
=225
Ω
, I
C2
=8mA and I
C6
=5mA.
From here it can be seen that the output voltage is approximately
3.1V to give relatively equal positive and negative output swings.
Diode Q
5
is included for bias purposes to allow direct coupling of
R
F2
to the base of Q
1
. The dual feedback loops stabilize the DC
operating point of the amplifier.
The output stage is a Darlington pair (Q
6
and Q
2
) which increases
the DC bias voltage on the input stage (Q
1
) to a more desirable
value, and also increases the feedback loop gain. Resistor R
0
optimizes the output VSWR (Voltage Standing Wave Ratio).
Inductors L
1
and L
2
are bondwire and lead inductances which are
roughly 3nH. These improve the high-frequency impedance
matches at input and output by partially resonating with 0.5pF of pad
and package capacitance.
VIN
L2
3nH
Q1
Q4
RF1
140
RE1
12
RF2
200
Q5
RE2
12
R3
140
Q6
10
3nH
L2
VOUT
R2
225
VCC
R1
650
R0
Q3
Q2
SR00231
Figure 17. Schematic Diagram
Philips Semiconductors
Product specification
SA5205A
Wide-band high-frequency amplifier
1997 Nov 07
8
POWER DISSIPATION CONSIDERATIONS
When using the part at elevated temperature, the engineer should con-
sider the power dissipation capabilities.
At the nominal supply voltage of 6V, the typical supply current is
25mA (32mA Max). For operation at supply voltages other than 6V,
see Figure 3 for I
CC
versus V
CC
curves. The supply current is
inversely proportional to temperature and varies no more than 1mA
between 25
°
C and either temperature extreme. The change is 0.1%
per over the range.
The recommended operating temperature ranges are air-mount
specifications. Better heat sinking benefits can be realized by
mounting the D package body against the PC board plane.
PC BOARD MOUNTING
In order to realize satisfactory mounting of the SA5205A to a PC
board, certain techniques need to be utilized. The board must be
double-sided with copper and all pins must be soldered to their
respective areas (i.e., all GND and V
CC
pins on the SO package).
The power supply should be decoupled with a capacitor as close to
the V
CC
pins as possible and an RF choke should be inserted
between the supply and the device. Caution should be exercised in
the connection of input and output pins. Standard microstrip should
be observed wherever possible. There should be no solder bumps
or burrs or any obstructions in the signal path to cause launching
problems. The path should be as straight as possible and lead
lengths as short as possible from the part to the cable connection.
Another important consideration is that the input and output should
be AC coupled. This is because at V
CC
=6V, the input is
approximately at 1V while the output is at 3.1V. The output must be
decoupled into a low impedance system or the DC bias on the
output of the amplifier will be loaded down causing loss of output
power. The easiest way to decouple the entire amplifier is by
soldering a high frequency chip capacitor directly to the input and
output pins of the device. This circuit is shown in Figure 18. Follow
these recommendations to get the best frequency response and
noise immunity. The board design is as important as the integrated
circuit design itself.
SCATTERING PARAMETERS
The primary specifications for the SA5205A are listed as
S-parameters. S-parameters are measurements of incident and
reflected currents and voltages between the source, amplifier and
load as well as transmission losses. The parameters for a two-port
network are defined in Figure 19.
Actual S-parameter measurements using an HP network analyzer
(model 8505A) and an HP S-parameter tester (models 8503A/B) are
shown in Figure 20.
Values for the figures below are measured and specified in the data
sheet to ease adaptation and comparison of the SA5205A to other
high-frequency amplifiers.
5205A
VOUT
VIN
VCC
AC
COUPLING
CAPACITOR
RF CHOKE
DECOUPLING
CAPACITOR
AC
COUPLING
CAPACITOR
SR00232
Figure 18. Circuit Schematic for Coupling and Power Supply
Decoupling
a. Two-Port Network Defined
b.
S21
S12
S22
S11
POWER AVAILABLE FROM
GENERATOR AT INPUT PORT
POWER REFLECTED
FROM INPUT PORT
S11 =
POWER REFLECTED
FROM OUTPUT PORT
POWER AVAILABLE FROM
GENERATOR AT OUTPUT PORT
S
22
=
REVERSE TRANSDUCER
POWER GAIN
S12 =
S11 — INPUT RETURN LOSS
S12 — REVERSE TRANSMISSION LOSS
OSOLATION
S21 — FORWARD TRANSMISSION LOSS
OR INSERTION GAIN
S21
= TRANSDUCER POWER GAIN
S22
— OUTPUT RETURN LOSS
SR00233
Figure 19.
Philips Semiconductors
Product specification
SA5205A
Wide-band high-frequency amplifier
1997 Nov 07
9
INPUT RETURN LOSS—dB
OUTPUT RETURN LOSS—dB
40
35
30
25
20
15
10
101
2
4