AD8350ARM20 [ROCHESTER]
1000MHz RF/MICROWAVE WIDE BAND MEDIUM POWER AMPLIFIER, PLASTIC, MICRO SOIC-8;
| 型号： | AD8350ARM20 |
| 厂家： | 
Rochester Electronics |
| 描述： | 1000MHz RF/MICROWAVE WIDE BAND MEDIUM POWER AMPLIFIER, PLASTIC, MICRO SOIC-8 放大器 射频 微波 功率放大器 |
| 文件： | 总17页 (文件大小：909K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Low Distortion
1.0 GHz Differential Amplifier
a
AD8350
FUNCTIONAL BLOCK DIAGRAM
FEATURES
8-Lead SOIC and ꢁSOIC Packages (with Enable)
High Dynamic Range
Output IP3: +28 dBm: Re 50 ꢀ @ 250 MHz
Low Noise Figure: 5.9 dB @ 250 MHz
Two Gain Versions:
AD8350-15: 15 dB
AD8350-20: 20 dB
–3 dB Bandwidth: 1.0 GHz
Single Supply Operation: 5 V to 10 V
Supply Current: 28 mA
IN+
IN–
1
2
3
4
8
7
6
5
–
+
ENBL
GND
GND
V
CC
OUT–
OUT+
AD8350
Input/Output Impedance: 200 ꢀ
Single-Ended or Differential Input Drive
8-Lead SOIC Package and 8-Lead microSOIC Package
APPLICATIONS
Cellular Base Stations
Communications Receivers
RF/IF Gain Block
Differential A-to-D Driver
SAW Filter Interface
Single-Ended-to-Differential Conversion
High Performance Video
High Speed Data Transmission
PRODUCT DESCRIPTION
The amplifier can be operated down to 5 V with an OIP3 of
+28 dBm at 250 MHz and slightly reduced distortion perfor-
mance. The wide bandwidth, high dynamic range and temperature
stability make this product ideal for the various RF and IF
frequencies required in cellular, CATV, broadband, instrumen-
tation and other applications.
The AD8350 series are high performance fully-differential
amplifiers useful in RF and IF circuits up to 1000 MHz. The
amplifier has excellent noise figure of 5.9 dB at 250 MHz. It
offers a high output third order intercept (OIP3) of +28 dBm
at 250 MHz. Gain versions of 15 dB and 20 dB are offered.
The AD8350 is designed to meet the demanding performance
requirements of communications transceiver applications. It
enables a high dynamic range differential signal chain, with
exceptional linearity and increased common-mode rejection.
The device can be used as a general purpose gain block, an
A-to-D driver, and high speed data interface driver, among
other functions. The AD8350 input can also be used as a single-
ended-to-differential converter.
The AD8350 is offered in an 8-lead single SOIC package and
µSOIC package. It operates from 5 V and 10 V power supplies,
drawing 28 mA typical. The AD8350 offers a power enable func-
tion for power-sensitive applications. The AD8350 is fabricated
using Analog Devices’ proprietary high speed complementary
bipolar process. The device is available in the industrial (–40°C to
+85°C) temperature range.
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, norforanyinfringementsofpatentsorotherrightsofthirdpartiesthat
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
www.analog.com
© Analog Devices, Inc., 2001
(@ 25ꢂC, VS = 5 V, G = 15 dB, unless otherwise noted. All specifications refer to
differential inputs and differential outputs unless noted.)
AD8350–SPECIFICATIONS
Parameter
Conditions
Min
Typ
Max
Unit
DYNAMIC PERFORMANCE
–3 dB Bandwidth
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
0.9
1.1
90
90
2000
10
15
0.003
–0.002
–18
GHz
GHz
MHz
MHz
V/µs
ns
Bandwidth for 0.1 dB Flatness
Slew Rate
V
OUT = 1 V p-p
Settling Time
0.1%, VOUT = 1 V p-p
VS = 5 V, f = 50 MHz
VS = 5 V to 10 V, f = 50 MHz
TMIN to TMAX
Gain (S21)1
14
16
dB
Gain Supply Sensitivity
Gain Temperature Sensitivity
Isolation (S12)1
dB/V
dB/°C
dB
f = 50 MHz
NOISE/HARMONIC PERFORMANCE
50 MHz Signal
Second Harmonic
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V
VS = 10 V
VS = 5 V
–66
–67
–65
–70
58
58
28
dBc
dBc
dBc
dBc
dBm
dBm
dBm
dBm
Third Harmonic
Output Second Order Intercept2
Output Third Order Intercept2
VS = 10 V
29
250 MHz Signal
Second Harmonic
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V
VS = 10 V
VS = 5 V
VS = 10 V
VS = 5 V
VS = 10 V
f = 150 MHz
–48
–49
–52
–61
39
40
24
28
2
5
1.7
6.8
dBc
dBc
dBc
dBc
dBm
dBm
dBm
dBm
dBm
dBm
nV/√Hz
dB
Third Harmonic
Output Second Order Intercept2
Output Third Order Intercept2
1 dB Compression Point (RTI)2
Voltage Noise (RTI)
Noise Figure
f = 150 MHz
INPUT/OUTPUT CHARACTERISTICS
Differential Offset Voltage (RTI)
Differential Offset Drift
Input Bias Current
Input Resistance
CMRR
V
OUT+ – VOUT–
1
0.02
15
200
–67
200
mV
mV/°C
µA
TMIN to TMAX
Real
f = 50 MHz
Real
Ω
dB
Ω
Output Resistance
POWER SUPPLY
Operating Range
Quiescent Current
4
25
3
27
3
11.0
32
5.5
34
V
Powered Up, VS = 5 V
Powered Down, VS = 5 V
Powered Up, VS = 10 V
Powered Down, VS = 10 V
28
3.8
30
4
15
–58
mA
mA
mA
mA
ns
6.5
Power-Up/Down Switching
Power Supply Rejection Ratio
f = 50 MHz, VS ∆ = 1 V p-p
dB
OPERATING TEMPERATURE RANGE
–40
+85
°C
NOTES
1See Tables II–III for complete list of S-Parameters.
2Re: 50 Ω.
Specifications subject to change without notice.
–2–
REV. A
AD8350
(@ 25ꢂC, VS = 5 V, G = 20 dB, unless otherwise noted. All specifications refer to
AD8350-20–SPECIFICATIONS
differential inputs and differential outputs unless noted.)
Parameter
Conditions
Min
Typ
Max
Unit
DYNAMIC PERFORMANCE
–3 dB Bandwidth
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VOUT = 1 V p-p
0.1%, VOUT = 1 V p-p
VS = 5 V, f = 50 MHz
0.7
0.9
90
90
2000
15
20
GHz
GHz
MHz
MHz
V/µs
ns
Bandwidth for 0.1 dB Flatness
Slew Rate
Settling Time
Gain (S21)1
19
21
dB
Gain Supply Sensitivity
Gain Temperature Sensitivity
Isolation (S12)1
VS = 5 V to 10 V, f = 50 MHz
0.003
–0.002
–22
dB/V
dB/°C
dB
TMIN to TMAX
f = 50 MHz
NOISE/HARMONIC PERFORMANCE
50 MHz Signal
Second Harmonic
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V
VS = 10 V
VS = 5 V
VS = 10 V
–65
–66
–66
–70
56
56
28
29
dBc
dBc
dBc
dBc
dBm
dBm
dBm
dBm
Third Harmonic
Output Second Order Intercept2
Output Third Order Intercept2
250 MHz Signal
Second Harmonic
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V, VOUT = 1 V p-p
VS = 10 V, VOUT = 1 V p-p
VS = 5 V
VS = 10 V
VS = 5 V
VS = 10 V
VS = 5 V
–45
–46
–55
–60
37
38
24
28
–2.6
1.8
1.7
5.6
dBc
dBc
dBc
dBc
dBm
dBm
dBm
dBm
dBm
dBm
nV/√Hz
dB
Third Harmonic
Output Second Order Intercept2
Output Third Order Intercept2
1 dB Compression Point (RTI)2
VS = 10 V
f = 150 MHz
f = 150 MHz
Voltage Noise (RTI)
Noise Figure
INPUT/OUTPUT CHARACTERISTICS
Differential Offset Voltage (RTI)
Differential Offset Drift
Input Bias Current
Input Resistance
CMRR
VOUT+ – VOUT–
TMIN to TMAX
1
0.02
15
200
–52
200
mV
mV/°C
µA
Real
f = 50 MHz
Real
Ω
dB
Ω
Output Resistance
POWER SUPPLY
Operating Range
Quiescent Current
4
25
3
27
3
11.0
32
5.5
34
V
Powered Up, VS = 5 V
Powered Down, VS = 5 V
Powered Up, VS = 10 V
Powered Down, VS = 10 V
28
3.8
30
4
15
–45
mA
mA
mA
mA
ns
6.5
Power-Up/Down Switching
Power Supply Rejection Ratio
f = 50 MHz, VS ∆ = 1 V p-p
dB
OPERATING TEMPERATURE RANGE
–40
+85
°C
NOTES
1See Tables II–III for complete list of S-Parameters.
2Re: 50 Ω.
–3–
REV. A
AD8350
PIN FUNCTION DESCRIPTIONS
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage, VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 V
Input Power Differential . . . . . . . . . . . . . . . . . . . . . . +8 dBm
Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . 400 mW
Pin Function
1, 8 IN+, IN–
Description
Differential Inputs. IN+ and IN–
should be ac-coupled (pins have a dc
bias of midsupply). Differential input
impedance is 200 Ω.
Power-up Pin. A high level (5 V) enables
the device; a low level (0 V) puts device
in sleep mode.
θ
θ
JA SOIC (R) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100°C/W
JA µSOIC (RM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133°C/W
Maximum Junction Temperature . . . . . . . . . . . . . . . . . 125°C
Operating Temperature Range . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature Range (Soldering 60 sec) . . . . . . . . . 300°C
2
3
ENBL
VCC
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
Positive Supply Voltage. 5 V to 10 V.
4, 5 OUT+, OUT– Differential Outputs. OUT+ and
OUT– should be ac-coupled (pins have
a dc bias of midsupply). Differential
input impedance is 200 Ω.
Common External Ground Reference.
PIN CONFIGURATION
6, 7 GND
1
2
3
4
8
7
6
5
IN–
IN+
GND
GND
OUT–
ENBL
AD8350
TOP VIEW
(Not to Scale)
V
CC
OUT+
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Option
Brand Code
AD8350AR15
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
8-Lead SOIC
SO-8
SO-8
SO-8
RM-8
RM-8
RM-8
SO-8
SO-8
SO-8
RM-8
RM-8
RM-8
Standard
Standard
Standard
J2N
J2N
J2N
Standard
Standard
Standard
J2P
J2P
J2P
AD8350AR15-REEL
AD8350AR15-REEL7
AD8350ARM15
AD8350ARM15-REEL
AD8350ARM15-REEL7
AD8350AR20
AD8350AR20-REEL
AD8350AR20-REEL7
AD8350ARM20
AD8350ARM20-REEL
AD8350ARM20-REEL7
AD8350-EVAL
8-Lead SOIC 13" Reel
8-Lead SOIC 7" Reel
8-Lead microSOIC
8-Lead microSOIC 13" Reel
8-Lead microSOIC 7" Reel
8-Lead SOIC
8-Lead SOIC 13" Reel
8-Lead SOIC 7" Reel
8-Lead microSOIC
8-Lead microSOIC 13" Reel
8-Lead microSOIC 7" Reel
SOIC Evaluation Board
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the AD8350 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
–4–
REV. A
Typical Performance Characteristics–AD8350
20
15
10
25
50
40
30
20
V
= 10V
CC
20
15
10
5
V
= 10V
V
= 10V
CC
CC
V
= 5V
CC
V
= 5V
CC
5
0
10
0
V
= 5V
CC
0
–40
–20
20
40
60
80
1
10
100
1k
10k
1
10
100
1k
10k
TEMPERATURE – ꢂC
FREQUENCY – MHz
FREQUENCY – MHz
TPC 2. AD8350-15 Gain (S21) vs.
Frequency
TPC 3. AD8350-20 Gain (S21) vs.
Frequency
TPC 1. Supply Current vs.
Temperature
350
300
250
500
350
300
400
SOIC
300
250
200
150
100
SOIC
V
= 10V
CC
V
= 10V
CC
200
100
0
200
150
100
V
= 5V
CC
V
= 5V
CC
0
10
100
1000
1
10
100
1k
1
10
100
1k
FREQUENCY – MHz
FREQUENCY – MHz
FREQUENCY – MHz
TPC 4. AD8350-15 Input Imped-
ance vs. Frequency
TPC 5. AD8350-20 Input Impedance
vs. Frequency
TPC 6. AD8350-15 Output Impedance
vs. Frequency
–5
–10
–15
–10
–15
800
ꢁSOIC
600
V
= 10V
= 5V
CC
400
200
0
SOIC
–20
–25
–30
V
= 10V
CC
V
–20
–25
CC
V
= 5V
CC
0
10
100
1000
1
10
100
1k
10k
1
10
100
1k
10k
FREQUENCY – MHz
FREQUENCY – MHz
FREQUENCY – MHz
TPC 7. AD8350-20 Output Imped-
ance vs. Frequency
TPC 8. AD8350-15 Isolation (S12)
vs. Frequency
TPC 9. AD8350-20 Isolation (S12)
vs. Frequency
–5–
REV. A
AD8350
–45
–55
–65
–75
–85
–40
–40
–45
–50
–55
–60
–65
–70
–75
–80
F
= 50MHz
O
V
= 1V p-p
V
= 1V p-p
OUT
OUT
–45
–50
–55
–60
–65
–70
–75
–80
HD2 (V = 10V)
CC
HD3 (V = 5V)
CC
HD2 (V = 5V)
CC
HD2 (V = 5V)
HD2 (V = 5V)
CC
CC
HD2 (V = 10V)
CC
HD3 (V = 5V)
CC
HD2 (V = 10V)
CC
HD3 (V = 5V)
CC
HD3 (V = 10V)
CC
HD3 (V = 10V)
CC
HD3 (V = 10V)
CC
0
0.5
1
1.5
2
2.5
3
3.5
0
0
50
100
150
200
250
300
50
100
150
200
250
300
OUTPUT VOLTAGE – V p-p
FUNDAMENTAL FREQUENCY – MHz
FUNDAMENTAL FREQUENCY – MHz
TPC 12. AD8350-15 Harmonic Distor-
tion vs. Differential Output Voltage
TPC 10. AD8350-15 Harmonic
Distortion vs. Frequency
TPC 11. AD8350-20 Harmonic Dis-
tortion vs. Frequency
66
61
–45
–55
–65
–75
–85
66
61
F
= 50MHz
O
HD2 (V = 5V)
CC
HD3 (V = 5V)
CC
V
= 10V
CC
V
= 10V
CC
56
51
46
41
36
56
51
46
41
36
HD2 (V = 10V)
CC
V
= 5V
V
= 5V
CC
CC
HD3 (V = 10V)
CC
0
0
0.5
1
1.5
2
2.5
3
3.5
0
50
100
150
200
250
300
50
100
150
200
250
300
FREQUENCY – MHz
OUTPUT VOLTAGE – V p-p
FREQUENCY – MHz
TPC 15. AD8350-20 Output Referred
IP2 vs. Frequency
TPC 13. AD8350-20 Harmonic Distor-
tion vs. Differential Output Voltage
TPC 14. AD8350-15 Output Referred
IP2 vs. Frequency
41
36
41
36
10.0
INPUT REFERRED
V
= 10V
7.5
CC
V
= 10V
V
= 10V
CC
CC
31
26
21
16
11
31
26
21
16
11
5.0
2.5
0
V
= 5V
CC
V
= 5V
CC
V
= 5V
200
CC
–2.5
–5.0
0
0
0
100
200
300
400
500
600
50
100
150
200
250
300
50
100
150
250
300
FREQUENCY – MHz
FREQUENCY – MHz
FREQUENCY – MHz
TPC 18. AD8350-15 1 dB Compres-
sion vs. Frequency
TPC 16. AD8350-15 Output Referred
IP3 vs. Frequency
TPC 17. AD8350-20 Output Referred
IP3 vs. Frequency
–6–
REV. A
AD8350
10
9
7.5
10
9
INPUT REFERRED
5.0
2.5
0
V
= 10V
CC
8
8
V
= 10V
CC
V
= 10V
CC
7
7
–2.5
V
= 5V
CC
V
= 5V
CC
6
V
= 5V
6
CC
–5.0
–7.5
5
5
0
0
0
100
200
300
400
500
600
50 100 150 200 250 300 350 400 450 500
50 100 150 200 250 300 350 400 450 500
FREQUENCY – MHz
FREQUENCY – MHz
FREQUENCY – MHz
TPC 19. AD8350-20 1 dB Compres-
sion vs. Frequency
TPC 20. AD8350-15 Noise Figure
vs. Frequency
TPC 21. AD8350-20 Noise Figure
vs. Frequency
–20
25
100
50
AD8350-20
V
= 5V
CC
20
15
–30
–40
–50
–60
–70
V
+ (V = 5V)
CC
OUT
0
–50
10
5
AD8350-15
V
– (V = 5V)
CC
OUT
AD8350-20
0
–100
–150
V
+ (V = 10V)
CC
OUT
–5
AD8350-15
–10
–15
–20
V
– (V = 10V)
CC
OUT
–80
–90
–200
–250
1
2
3
4
5
6
7
8
9
10
0
–40
–20
20
40
60
80
1
10
100
1k
V
– Volts
TEMPERATURE – ꢂC
FREQUENCY – MHz
CC
TPC 22. AD8350 Gain (S21) vs.
Supply Voltage
TPC 23. AD8350 Output Offset Volt-
age vs. Temperature
TPC 24. AD8350 PSRR vs. Frequency
–20
V
= 5V
V
= 5V
500mV
CC
CC
–30
–40
–50
–60
–70
AD8350-20
V
OUT
AD8350-15
ENBL
–80
–90
5V
30ns
1
10
100
1k
FREQUENCY – MHz
TPC 25. AD8350 CMRR vs. Frequency
TPC 26. AD8350 Power-Up/Down
Response Time
REV. A
–7–
AD8350
C
C
AC
L
/2
L /2
S
AC
APPLICATIONS
S
Using the AD8350
8
7
6
5
Figure 1 shows the basic connections for operating the AD8350.
A single supply in the range 5 V to 10 V is required. The power
supply pin should be decoupled using a 0.1 µF capacitor. The
R
/2
S
S
AD8350
C
–
C
P
P
V
R
S
LOAD
ENBL pin is tied to the positive supply or to 5 V (when VCC
=
10 V) for normal operation and should be pulled to ground to
put the device in sleep mode. Both the inputs and the outputs
have dc bias levels at midsupply and should be ac-coupled.
R
/2
1
2
3
4
L
/2
L /2
S
S
Also shown in Figure 1 are the impedance balancing requirements,
either resistive or reactive, of the input and output. With an
input and output impedance of 200 Ω, the AD8350 should be
driven by a 200 Ω source and loaded by a 200 Ω impedance. A
reactive match can also be implemented.
C
C
AC
AC
0.1ꢁF
ENBL (5V)
+V (5V TO 10V)
S
Figure 3. Reactively Matching the Input and Output
C2
0.001ꢁF
C4
0.001ꢁF
SOURCE
Z = 100ꢀ
LOAD
C
C
AC
L
AC
L
S
S
8
7
6
5
8
7
6
AD8350
5
R
S
AD8350
–
Z = 200ꢀ
C
–
C
P
P
V
R
S
LOAD
1
2
3
4
Z = 100ꢀ
1
2
3
4
C1
C3
0.001ꢁF
0.001ꢁF
C5
C
C
AC
AC
0.1ꢁF
ENBL (5V)
0.1ꢁF
ENBL (5V)
+V (5V TO 10V)
S
+V (5VTO 10V)
S
Figure 1. Basic Connections for Differential Drive
Figure 4. Single-Ended Equivalent Circuit
Figure 2 shows how the AD8350 can be driven by a single-
ended source. The unused input should be ac-coupled to ground.
When driven single-endedly, there will be a slight imbalance in
the differential output voltages. This will cause an increase in
When the source impedance is smaller than the load impedance,
a step-up matching network is required. A typical step-up network
is shown on the input of the AD8350 in Figure 3. For purely
resistive source and load impedances the resonant approach may
be used. The input and output impedance of the AD8350 can be
modeled as a real 200 Ω resistance for operating frequencies less
than 100 MHz. For signal frequencies exceeding 100 MHz, classi-
cal Smith Chart matching techniques should be invoked in order
to deal with the complex impedance relationships. Detailed S
parameter data measured differentially in a 200 Ω system can be
found in Tables II and III.
the second order harmonic distortion (at 50 MHz, with VCC
=
10 V and VOUT = 1 V p-p, –59 dBc was measured for the second
harmonic on AD8350-15).
LOAD
C2
0.001ꢁF
C4
0.001ꢁF
8
1
7
6
5
4
AD8350
–
For the input matching network the source resistance is less
than the input resistance of the AD8350. The AD8350 has a
nominal 200 Ω input resistance from Pins 1 to 8. The reactance
of the ac-coupling capacitors, CAC, should be negligible if 100 nF
capacitors are used and the lowest signal frequency is greater
than 1 MHz. If the series reactance of the matching network
inductor is defined to be XS = 2 π f LS, and the shunt reactance
of the matching capacitor to be XP = (2 π f CP)–1, then:
Z = 200ꢀ
2
3
SOURCE
Z = 200ꢀ
C3
0.001ꢁF
C5
0.1ꢁF
C1
0.001ꢁF
ENBL (5V)
+V (5V TO 10V)
S
RS × RLOAD
RS
XS =
where XP = RLOAD ×
Figure 2. Basic Connections for Single-Ended Drive
(1)
XP
RLOAD – RS
Reactive Matching
For a 70 MHz application with a 50 Ω source resistance, and
assuming the input impedance is 200 Ω, or RLOAD = RIN = 200 Ω,
then XP = 115.5 Ω and XS = 86.6 Ω, which results in the follow-
ing component values:
In practical applications, the AD8350 will most likely be matched
using reactive matching components as shown in Figure 3.
Matching components can be calculated using a Smith Chart or
by using a resonant approach to determine the matching network
that results in a complex conjugate match. In either situation,
the circuit can be analyzed as a single-ended equivalent circuit
to ease calculations as shown in Figure 4.
CP = (2 π × 70 × 106 × 115.5)–1 = 19.7 pF and
LS = 86.6 × (2 π × 70 × 106)–1 = 197 nH
–8–
REV. A
AD8350
For the output matching network, if the output source resis-
tance of the AD8350 is greater than the terminating load
resistance, a step-down network should be employed as shown
on the output of Figure 3. For a step-down matching network,
the series and parallel reactances are calculated as:
The same results could be found using a Smith Chart as shown
in Figure 7. In this example, a shunt capacitor and a series inductor
are used to match the 200 Ω source to a 50 Ω load. For a fre-
quency of 10 MHz, the same capacitor and inductor values
previously found using the resonant approach will transform the
200 Ω source to match the 50 Ω load. At frequencies exceeding
100 MHz, the S parameters from Tables II and III should be
used to account for the complex impedance relationships.
RS × RLOAD
RLOAD
XS =
where XP = RS ×
(2)
XP
RS – RLOAD
For a 10 MHz application with the 200 Ω output source resistance
of the AD8350, RS = 200 Ω, and a 50 Ω load termination, RLOAD
50 Ω, then XP = 115.5 Ω and XS = 86.6 Ω, which results in
the following component values:
=
CP = (2 π × 10 × 106 × 115.5)–1 = 138 pF and
LS = 86.6 × (2 π × 10 × 106)–1 = 1.38 µH
SOURCE
LOAD
The same results can be obtained using the plots in Figure 5
and Figure 6. Figure 5 shows the normalized shunt reactance
versus the normalized source resistance for a step-up matching
network, RS < RLOAD. By inspection, the appropriate reactance
can be found for a given value of RS/RLOAD. The series reactance
is then calculated using XS = RS RLOAD/XP. The same technique
can be used to design the step-down matching network using
Figure 6.
SHUNT C
SERIES L
2
Figure 7. Smith Chart Representation of Step-Down Network
1.8
1.6
1.4
1.2
1
R
SOURCE
X
S
After determining the matching network for the single-ended
equivalent circuit, the matching elements need to be applied in a
differential manner. The series reactance needs to be split such
that the final network is balanced. In the previous examples, this
simply translates to splitting the series inductor into two equal
halves as shown in Figure 3.
R
X
LOAD
P
0.8
0.6
0.4
0.2
0
Gain Adjustment
The effective gain of the AD8350 can be reduced using a num-
ber of techniques. Obviously a matched attenuator network will
reduce the effective gain, but this requires the addition of a
separate component which can be prohibitive in size and cost.
The attenuator will also increase the effective noise figure resulting
in an SNR degradation. A simple voltage divider can be imple-
mented using the combination of the driving impedance of the
previous stage and a shunt resistor across the inputs of the AD8350
as shown in Figure 8. This provides a compact solution but
suffers from an increased noise spectral density at the input
of the AD8350 due to the thermal noise contribution of the
shunt resistor. The input impedance can be dynamically altered
through the use of feedback resistors as shown in Figure 9. This
will result in a similar attenuation of the input signal by virtue
of the voltage divider established from the driving source imped-
ance and the reduced input impedance of the AD8350. Yet
this technique does not significantly degrade the SNR with
the unnecessary increase in thermal noise that arises from a truly
resistive attenuator network.
NORMALIZED SOURCE RESISTANCE – R
/R
LOAD
SOURCE
Figure 5. Normalized Step-Up Matching Components
3.2
R
SOURCE
X
S
3
2.8
2.6
2.4
2.2
2
R
X
LOAD
P
NORMALIZED SOURCE RESISTANCE – R
/R
LOAD
SOURCE
Figure 6. Normalized Step-Down Matching Components
REV. A
–9–
AD8350
C
C
AC
AC
The insertion loss and the resultant power gain for multiple
shunt resistor values is summarized in Table I. The source
resistance and input impedance need careful attention when
using Equation 1. The reactance of the input impedance of the
AD8350 and the ac-coupling capacitors need to be considered
before assuming they have negligible contribution. Figure 10
shows the effective power gain for multiple values of RSHUNT for
the AD8350-15 and AD8350-20.
8
7
6
5
R
R
R
S
L
L
R
SHUNT
AD8350
–
V
S
R
R
S
SHUNT
1
2
3
4
Table I. Gain Adjustment Using Shunt Resistor,
RS = 100 ꢀ and RIN = 100 ꢀ Single-Ended
C
C
AC
AC
0.1ꢁF
ENBL (5V)
Power Gain–dB
+V (5VTO 10V)
S
RSHUNT–ꢀ
IL–dB
AD8350-15
AD8350-20
Figure 8. Gain Reduction Using Shunt Resistor
50
6.02
3.52
1.94
1.34
1.02
8.98
13.98
16.48
18.06
18.66
18.98
100
200
300
400
11.48
13.06
13.66
13.98
R
FEXT
C
C
AC
AC
8
7
6
5
20
18
16
14
12
10
8
R
R
R
S
S
L
L
AD8350
–
V
AD8350-20
S
R
1
2
3
4
AD8350-15
0.1ꢁF
C
C
AC
AC
ENBL
(5V)
+V
6
S
(5V TO 10V)
4
R
FEXT
2
Figure 9. Dynamic Gain Reduction
0
0
100
200
300
400
500
600
700
800
R
– ꢀ
SHUNT
Figure 8 shows a typical implementation of the shunt divider
concept. The reduced input impedance that results from the
parallel combination of the shunt resistor and the input impedance
of the AD8350 adds attenuation to the input signal effectively
reducing the gain. For frequencies less than 100 MHz, the input
impedance of the AD8350 can be modeled as a real 200 Ω resis-
tance (differential). Assuming the frequency is low enough to
ignore the shunt reactance of the input, and high enough such
that the reactance of moderately sized ac-coupling capacitors
can be considered negligible, the insertion loss, IL, due to the
shunt divider can be expressed as:
Figure 10. Gain for Multiple Values of Shunt Resistance
for Circuit in Figure 8
The gain can be adjusted dynamically by employing external
feedback resistors as shown in Figure 9. The effective attenua-
tion is a result of the lowered input impedance as with the shunt
resistor method, yet there is no additional noise contribution at
the input of the device. It is necessary to use well-matched resistors
to minimize common-mode offset errors. Quality 1% tolerance
resistors should be used along with a symmetric board layout to
help guarantee balanced performance. The effective gain for mul-
tiple values of external feedback resistors is shown in Figure 11.
RIN
(RIN + RS )
RINꢀRSHUNT
IL(dB) = 20 × Log10
(RINꢀRSHUNT + RS )
(3)
where
RIN × RSHUNT
RIN + RSHUNT
RINꢀRSHUNT
=
and RIN = 100Ω single−ended
–10–
REV. A
AD8350
20
18
16
14
12
10
8
Driving Lighter Loads
It is not necessary to load the output of the AD8350 with a
200 Ω differential load. Often it is desirable to try to achieve a
complex conjugate match between the source and load in order
to minimize reflections and conserve power. But if the AD8350
is driving a voltage responding device, such as an ADC, it is no
longer necessary to maximize power transfer. The harmonic
distortion performance will actually improve when driving
loads greater than 200 Ω. The lighter load requires less cur-
rent driving capability on the output stages of the AD8350
resulting in improved linearity. Figure 12 shows the improve-
ment in second and third harmonic distortion for increasing
differential load resistance.
AD8350-20
AD8350-15
6
4
2
0
0
500
1000
– ꢀ
1500
2000
–66
–68
R
FEXT
Figure 11. Power Gain vs. External Feedback Resistors
for the AD8350-15 and AD8350-20 with RS = 100 Ω and
RL = 100 Ω
–70
HD3
–72
The power gain of any two-port network is dependent on the
source and load impedance. The effective gain will change if the
differential source and load impedance is not 200 Ω. The single-
ended input and output resistance of the AD8350 can be modeled
using the following equations:
–74
–76
–78
HD2
–80
RF + RL
RIN
=
RF + RL
(4)
+1+ gm × RL
–82
200
RINT
300
400
500
600
– ꢀ
700
800
900
1000
R
LOAD
and
Figure 12. Second and Third Harmonic Distortion vs.
Differential Load Resistance for the AD8350-15 with
VS = 5 V, f = 70 MHz, and VOUT = 1 V p-p
1
RF +
1
1
+
RF + RS
1+ gm × RS
RS RINT
ROUT
=
≈
for RS ≤ 1kΩ
1
(5)
1+ gm ×
1
1
+
RS RINT
where
RF
= RFEXT//RFINT
RFEXT = R Feedback External
RFINT = 662 Ω for the AD8350-15
= 1100 Ω for the AD8350-20
RINT = 25000 Ω
gm
= 0.066 mhos for the AD8350-15
= 0.110 mhos for the AD8350-20
= R Source (Single-Ended)
= R Load (Single-Ended)
RS
RL
RIN
= R Input (Single-Ended)
ROUT = R Output (Single-Ended)
The resultant single-ended gain can be calculated using the
following equation:
R × g × R −1
RL + RS + RF + RL × RS × gm
(
)
L
m
F
GV =
(6)
REV. A
–11–
AD8350
EVALUATION BOARD
To drive and load the board differentially, transformers T1 and
T2 should be removed and replaced with four 0 Ω resistors
(0805 size); Resistors R1 and R4 (0 Ω) should also be removed.
This yields a circuit with a broadband input and output impedance
of 200 Ω. To match to impedances other than this, matching
components (0805 size) can be placed on pads C1, C2, C3, C4,
L1, and L2.
Figure 13 shows the schematic of the AD8350 evaluation board,
for SOIC, as it is shipped from the factory. The board is config-
ured to allow easy evaluation using single-ended 50 Ω test
equipment. The input and output transformers have a 4-to-1
impedance ratio and transform the AD8350’s 200 Ω input and
output impedances to 50 Ω. In this mode, 0 Ω resistors (R1 and
R4) are required.
To allow compensation for the insertion loss of the transform-
ers, a calibration path is provided at Test In and Test Out. This
consists of two transformers connected back to back.
C3
0.001ꢁF
C1
0.001ꢁF
8
1
7
6
5
4
R1
0ꢀ
R4
0ꢀ
T1: TC4-1W
T2: TC4-1W
(MINI CIRCUITS)
AD8350
(MINI CIRCUITS)
6
1
R2
0ꢀ
R3
0ꢀ
IN–
OUT–
–
L2
(OPEN)
L1
(OPEN)
1
6
IN+
OUT+
2
3
C2
0.001ꢁF
C4
0.001ꢁF
C5
0.1ꢁF
A
B
3
2
+V
S
SW1
1
+V
S
T3: TC4-1W
T4: TC4-1W
(MINI CIRCUITS)
(MINI CIRCUITS)
6
1
TEST IN
TEST OUT
1
6
Figure 13. Evaluation Board
–12–
REV. A
AD8350
Table II. Typical Scattering Parameters for the AD8350-15: VCC = 5 V, Differential Input and Output, ZSOURCE(diff) = 200 ꢀ,
ZLOAD(diff) = 200 ꢀ
Frequency – MHz
S11
S12
S21
S22
25
50
75
0.015∠–48.8°
0.028∠–65.7°
0.043∠–75.3°
0.057∠–87.5°
0.073∠–91.8°
0.080∠–95.6°
0.100∠–97.4°
0.111∠–99.1°
0.128∠–103.2°
0.141∠–106.7°
0.151∠–109.7°
0.161∠–111.9°
0.179∠–114.7°
0.187∠–117.4°
0.194∠–121°
0.199∠–121.2°
0.215∠–122.6°
0.225∠–127.0°
0.225∠–127.7°
0.244∠–129.9°
0.119∠176.3°
0.119∠171.1°
0.119∠166.9°
0.120∠163.5°
0.119∠159.8°
0.120∠154.8°
0.117∠151.2°
0.121∠147.3°
0.120∠143.7°
0.120∠140.3°
0.120∠136.6°
0.123∠132.9°
0.121∠130.7°
0.122∠126.6°
0.123∠123.6°
0.124∠120.1°
0.126∠117.2°
0.126∠113.9°
0.126∠112°
5.60∠–4.3°
5.61∠–8.9°
5.61∠–13.5°
5.61∠–17.9°
5.65∠–22.6°
5.68∠–27.0°
5.73∠–31.8°
5.78∠–36.3°
5.83∠–41.0°
5.90∠–45.6°
6.02∠–50.2°
6.14∠–55.1°
6.19∠–60.2°
6.27∠–65.0°
6.43∠–70.1°
6.61∠–75.8°
6.77∠–81.7°
6.91∠–87.6°
7.06∠–93.8°
7.27∠–99.8°
0.034∠–4.8°
0.032∠–14.3°
0.036∠–30.2°
0.043∠–39.6°
0.053∠–40.6°
0.058∠–37°
0.072∠–45.1°
0.077∠–47.7°
0.091∠–52.5°
0.104∠–55.1°
0.108∠–54.2°
0.122∠–51.5°
0.135∠–55.6°
0.150∠–56.9°
0.162∠–60.9°
0.187∠–60.3°
0.215∠–63.3°
0.242∠–63.9°
0.268∠–65.2°
0.304∠–68.2°
100
125
150
175
200
225
250
275
300
325
350
375
400
425
450
475
500
0.128∠108.1°
Table III. Typical Scattering Parameters for the AD8350-20: VCC = 5 V, Differential Input and Output, ZSOURCE(diff) = 200 ꢀ,
LOAD(diff) = 200 ꢀ
Z
Frequency – MHz
S11
S12
S21
S22
25
50
75
0.017∠–142.9°
0.033∠–114.9°
0.055∠–110.6°
0.073∠–109.4°
0.089∠–112.1°
0.098∠–116.5°
0.124∠–118.1°
0.141∠–119.4°
0.159∠–122.6°
0.170∠–128.5°
0.186∠–131.6°
0.203∠–132.9°
0.215∠–135.0°
0.222∠–136.9°
0.242∠–142.4°
0.240∠–145.2°
0.267∠–146.7°
0.266∠–150.7°
0.267∠–153.7°
0.285∠–161.1°
0.074∠174.9°
0.074∠171.0°
0.075∠167.0°
0.075∠163.1°
0.075∠159.2°
0.076∠153.8°
0.075∠150.2°
0.076∠147.2°
0.077∠142.2°
0.078∠139.5°
0.078∠135.8°
0.080∠132.5°
0.080∠129.3°
0.082∠125.9°
0.082∠123.6°
0.084∠120.3°
0.084∠117.3°
0.086∠115.1°
0.087∠112.8°
0.088∠110.9°
9.96∠–4.27°
9.98∠–8.9°
0.023–16.6°
0.022∠–2.7°
0.023∠–23.5°
0.029∠–22.7°
0.037∠–18.0°
0.045∠–3.2°
0.055∠–15.7°
0.065∠–15.6°
0.080∠–17.7°
0.085∠–22.4°
0.096∠–23.5°
0.116∠–25.9°
0.139∠–29.6°
0.161∠–32.2°
0.173∠–38.6°
0.207∠–37.6°
0.241∠–48.1°
0.265∠–49.7°
0.317∠–53.5°
0.359∠–59.2°
9.98∠–13.3°
10.00∠–17.7°
10.12∠–22.1°
10.20∠–26.4°
10.34∠–30.9°
10.50∠–35.6°
10.65∠–40.1°
10.80∠–44.7°
11.14∠–49.3°
11.45∠–54.7°
11.70∠–60.3°
11.93∠–65.0°
12.39∠–70.3°
12.99∠–76.8°
13.34∠–84.0°
13.76∠–90.1°
14.34∠–97.5°
14.89∠–105.0°
100
125
150
175
200
225
250
275
300
325
350
375
400
425
450
475
500
REV. A
–13–
AD8350
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic SOIC
(SO-8)
0.1968 (5.00)
0.1890 (4.80)
8
1
5
4
0.2440 (6.20)
0.2284 (5.80)
0.1574 (4.00)
0.1497 (3.80)
PIN 1
0.0196 (0.50)
0.0099 (0.25)
0.0500 (1.27)
BSC
ꢃ 45ꢂ
0.0688 (1.75)
0.0532 (1.35)
0.0098 (0.25)
0.0040 (0.10)
8ꢂ
0ꢂ
0.0500 (1.27)
0.0160 (0.41)
0.0192 (0.49)
0.0138 (0.35)
0.0098 (0.25)
0.0075 (0.19)
SEATING
PLANE
8-Lead microSOIC Package
(RM-8)
0.122 (3.10)
0.114 (2.90)
8
5
4
0.122 (3.10)
0.114 (2.90)
0.199 (5.05)
0.187 (4.75)
1
PIN 1
0.0256 (0.65) BSC
0.120 (3.05)
0.112 (2.84)
0.120 (3.05)
0.112 (2.84)
0.043 (1.09)
0.037 (0.94)
0.006 (0.15)
0.002 (0.05)
33ꢂ
0.018 (0.46)
0.008 (0.20)
27ꢂ
0.028 (0.71)
0.016 (0.41)
0.011 (0.28)
0.003 (0.08)
SEATING
PLANE
–14–
REV. A
–15–
–16–
相关型号：
AD8350ARZ20
<span class="noTransform">1.0 GHz </span>Differential Amplifier Package: 8 ld SOIC; No of Pins: 8; Temperature Range: Industrial; Container: 0/Tube
ADI
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