AD AD8055 Low cost, 300 mhz voltage feedback amplifier Datasheet

a
FEATURES
Low Cost Single (AD8055) and Dual (AD8056)
Easy to Use Voltage Feedback Architecture
High Speed
300 MHz, –3 dB Bandwidth (G = +1)
1400 V/␮s Slew Rate
20 ns Settling to 0.1%
Low Distortion: –72 dBc @ 10 MHz
Low Noise: 6 nV/√Hz
Low DC Errors: 5 mV Max VOS, 1.2 ␮A Max IB
Small Packaging
AD8055 Available in SOT-23-5
AD8056 Available in 8-Lead microSOIC
Excellent Video Specifications (RL = 150 ⍀, G = +2)
Gain Flatness 0.1 dB to 40 MHz
0.01% Differential Gain Error
0.02ⴗ Differential Phase Error
Drives Four Video Loads (37.5 ⍀) with 0.02% and
0.1ⴗ Differential Gain and Differential Phase
Low Power, ⴞ5 V Supplies
5 mA Typ/Amplifier Power Supply Current
High Output Drive Current: Over 60 mA
APPLICATIONS
Imaging
Photodiode Preamp
Video Line Driver
Differential Line Driver
Professional Cameras
Video Switchers
Special Effects
A-to-D Driver
Active Filters
Low Cost, 300 MHz
Voltage Feedback Amplifiers
AD8055/AD8056
FUNCTIONAL BLOCK DIAGRAMS
N-8 and SO-8
AD8055
NC 1
7 +VS
+IN 3
6 VOUT
–VS 4
Despite their low cost, the AD8055 and AD8056 provide excellent overall performance. For video applications, their differential gain and phase error are 0.01% and 0.02° into a 150 Ω load,
and 0.02% and 0.1° while driving four video loads (37.5 Ω).
Their 0.1 dB flatness out to 40 MHz, wide bandwidth out to
300 MHz, along with 1400 V/µs slew rate and 20 ns settling
time, make them useful for a variety of high speed applications.
VOUT 1
5 +VS
–VS 2
+IN 3
5 NC
(Not to Scale)
4 –IN
(Not to Scale)
NC = NO CONNECT
N-8, SO-8, microSOIC (RM)
AD8056
OUT1 1
8 +VS
–IN1 2
7 OUT
+IN1 3
6 –IN2
–VS 4
5 +IN2
(Not to Scale)
The AD8055 and AD8056 require only 5 mA typ/amplifier of
supply current and operate on dual ± 5 V or single +12 V power
supply, while being capable of delivering over 60 mA of load
current. All this is offered in a small 8-lead plastic DIP, 8-lead
SOIC packages, 5-lead SOT-23-5 package (AD8055) and an
8-lead microSOIC package (AD8056). These features make
the AD8055/AD8056 ideal for portable and battery powered
applications where size and power are critical. These amplifiers are
available in the industrial temperature range of –40°C to +85°C.
5
4
3
GAIN – dB
The AD8055 (single) and AD8056 (dual) voltage feedback
amplifiers offer bandwidth and slew rate typically found in current feedback amplifiers. Additionally, these amplifiers are easy
to use and available at a very low cost.
AD8055
8 NC
–IN 2
RC
VIN
VOUT
50⍀
2
PRODUCT DESCRIPTION
SOT-23-5 (RT)
RS
RL
RF
VOUT = 100mV p-p
RL = 100⍀
G = +1
RF = 0⍀
RC = 100⍀
1
G = +2
RF = 402⍀
0
–1
–2
G = +10
RF = 909⍀
–3
G = +5
RF = 1000⍀
–4
–5
0.3M
1M
10M
100M
FREQUENCY – Hz
1G
Figure 1. Frequency Response
REV. B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which 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
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2000
+25ⴗC, V = 65 V, R = 402 ⍀, R = 100 ⍀, Gain = +2,
AD8055/AD8056–SPECIFICATIONS (@unlessT =otherwise
noted)
A
S
Model
Bandwidth for 0.1 dB Flatness
Slew Rate
Settling Time to 0.1%
Rise and Fall Time, 10% to 90%
NOISE/HARMONIC PERFORMANCE
Total Harmonic Distortion
Crosstalk, Output to Output (AD8056)
Input Voltage Noise
Input Current Noise
Differential Gain Error
Differential Phase Error
L
AD8055A/AD8056A
Min
Typ
Max
Conditions
DYNAMIC PERFORMANCE
–3 dB Bandwidth
F
G = +1, VO = 0.1 V p-p
G = +1, VO = 2 V p-p
G = +2, VO = 0.1 V p-p
G = +2, VO = 2 V p-p
VO = 100 mV p-p
G = +1, VO = 4 V Step
G = +2, VO = 4 V Step
G = +2, VO = 2 V Step
G = +1, VO = 0.5 V Step
G = +1, VO = 4 V Step
G = +2, VO = 0.5 V Step
G = +2, VO = 4 V Step
220
125
120
125
25
1000
750
fC = 10 MHz, VO = 2 V p-p, RL = 1 kΩ
fC = 20 MHz, VO = 2 V p-p, RL = 1 kΩ
f = 5 MHz, G = +2
f = 100 kHz
f = 100 kHz
NTSC, G = +2, RL = 150 Ω
NTSC, G = +2, RL = 37.5 Ω
NTSC, G = +2, RL = 150 Ω
NTSC, G = +2, RL = 37.5 Ω
DC PERFORMANCE
Input Offset Voltage
300
150
160
150
40
1400
840
20
2
2.7
2.8
4
MHz
MHz
MHz
MHz
MHz
V/µs
V/µs
ns
ns
ns
ns
ns
–72
–57
–60
6
1
0.01
0.02
0.02
0.1
dBc
dBc
dB
nV/√Hz
pA/√Hz
%
%
Degree
Degree
3
TMIN –TMAX
Offset Drift
Input Bias Current
Open Loop Gain
INPUT CHARACTERISTICS
Input Resistance
Input Capacitance
Input Common-Mode Voltage Range
Common-Mode Rejection Ratio
OUTPUT CHARACTERISTICS
Output Voltage Swing
Output Current1
Short Circuit Current1
POWER SUPPLY
Operating Range
Quiescent Current
Power Supply Rejection Ratio
TMIN –TMAX
VO = ± 2.5 V
TMIN –TMAX
66
64
AD8055
TMIN –TMAX
AD8056
TMIN –TMAX
+VS = +5 V to +6 V, –VS = –5 V
–VS = –5 V to –6 V, +VS = +5 V
OPERATING TEMPERATURE RANGE
6
0.4
1
71
5
10
1.2
mV
mV
µV/°C
µA
µA
dB
dB
10
2
3.2
82
MΩ
pF
±V
dB
2.9
55
3.1
60
110
±V
mA
mA
± 4.0
± 5.0
5.4
VCM = ± 2.5 V
RL = 150 Ω
VO = ± 2.0 V
Unit
10
66
69
–40
± 6.0
6.5
7.3
12
13.3
V
mA
mA
mA
mA
dB
dB
+85
°C
72
86
NOTES
1
Output current is limited by the maximum power dissipation in the package. See the power derating curves.
Specifications subject to change without notice.
–2–
REV. B
AD8055/AD8056
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 V
Internal Power Dissipation2
Plastic DIP Package (N) . . . . . . . . . . . . . . . . . . . . . . 1.3 W
Small Outline Package (R) . . . . . . . . . . . . . . . . . . . . . 0.8 W
SOT-23-5 Package (RT) . . . . . . . . . . . . . . . . . . . . . . 0.5 W
microSOIC Package (RM) . . . . . . . . . . . . . . . . . . . . . 0.6 W
Input Voltage (Common Mode) . . . . . . . . . . . . . . . . . . . ± VS
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . ± 2.5 V
Output Short Circuit Duration
. . . . . . . . . . . . . . . . . . . . . . Observe Power Derating Curves
Storage Temperature Range N, R . . . . . . . . –65°C to +125°C
Operating Temperature Range (A Grade) . . –40°C to +85°C
Lead Temperature Range (Soldering 10 sec) . . . . . . . +300°C
of the plastic, approximately +150°C. Exceeding this limit temporarily may cause a shift in parametric performance due to a
change in the stresses exerted on the die by the package. Exceeding
a junction temperature of +175°C for an extended period can
result in device failure.
While the AD8055/AD8056 are internally short circuit protected,
this may not be sufficient to guarantee that the maximum junction temperature (+150°C) is not exceeded under all conditions.
To ensure proper operation, it is necessary to observe the maximum power derating curves.
2.0
MAXIMUM POWER DISSIPATION – Watts
ABSOLUTE MAXIMUM RATINGS 1
NOTES
1
Stresses above those listed under Absolute Maximum Ratings may cause permanent 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.
2
Specification is for device in free air:
8-Lead Plastic DIP Package: θJA = 90°C/W
8-Lead SOIC Package: θJA = 155°C/W
5-Lead SOT-23-5 Package: θJA = 240°C/W
8-Lead microSOIC Package: θJA = 200°C/W
8-LEAD PLASTIC DIP PACKAGE
1.5
8-LEAD SOIC
PACKAGE
TJ = +150ⴗC
1.0
0.5
␮SOIC
SOT-23-5
0
–50 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90
AMBIENT TEMPERATURE – ⴗC
MAXIMUM POWER DISSIPATION
The maximum power that can be safely dissipated by the AD8055/
AD8056 is limited by the associated rise in junction temperature.
The maximum safe junction temperature for plastic encapsulated devices is determined by the glass transition temperature
Figure 2. Plot of Maximum Power Dissipation vs.
Temperature for AD8055/AD8056
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Option
Brand Code
AD8055AN
AD8055AR
AD8055AR-REEL
AD8055AR-REEL7
AD8055ART-REEL
AD8055ART-REEL7
–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
Plastic DIP
Small Outline Package (SOIC)
13" Tape and Reel
7" Tape and Reel
13" Tape and Reel
7" Tape and Reel
N-8
SO-8
SO-8
SO-8
RT-5
RT-5
H3A
H3A
AD8056AN
AD8056AR
AD8056AR-REEL
AD8056AR-REEL7
AD8056ARM
AD8056ARM-REEL
AD8056ARM-REEL7
–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
Plastic DIP
Small Outline Package (SOIC)
13" Tape and Reel
7" Tape and Reel
microSOIC
13" Tape and Reel
7" Tape and Reel
N-8
SO-8
SO-8
SO-8
RM-8
RM-8
RM-8
H5A
H5A
H5A
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 AD8055/AD8056 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.
REV. B
–3–
WARNING!
ESD SENSITIVE DEVICE
AD8055/AD8056–Typical Performance Characteristics
402⍀
+VS
+VS
4.7␮F
0.01␮F
0.001␮F
HP8130A
PULSE
GENERATOR
TR /TF = 1ns
VIN
100⍀
3
2
0.001␮F
HP8130A
PULSE
GENERATOR
TR/TF = 0.67ns
7
AD8055
50⍀
4
VOUT
6
4.7␮F
0.01␮F
4.7␮F
100⍀
VIN
402⍀
2
7
AD8055
57⍀
3
4
0.01␮F
6
VOUT
4.7␮F
100⍀
0.01␮F
0.001␮F
0.001␮F
–VS
–VS
Figure 3. Test Circuit, G = +1, RL = 100 Ω
Figure 6. Test Circuit, G = –1, RL = 100 Ω
Figure 4. Small Step Response, G = +1
Figure 7. Small Step Response, G = –1
Figure 5. Large Step Response, G = +1
Figure 8. Large Step Response, G = –1
–4–
REV. B
AD8055/AD8056
5
4
–50
RC
VIN
VOUT
VOUT = 100mV p-p
RL = 100⍀
RS
GAIN – dB
2
RF
RL
HARMONIC DISTORTION – dBc
50⍀
3
G = +2
RF = 402⍀
G = +1
RF = 0⍀
RC = 100⍀
1
0
–1
–2
G = +10
RF = 909⍀
–3
2ND
–70
–80
3RD
–90
G = +5
RF = 1000⍀
–4
–5
0.3M
VOUT = 2V p-p
G = +2
RL = 100⍀
–60
1M
–100
10k
1G
10M
100M
FREQUENCY – Hz
Figure 9. Small Signal Frequency Response,
G = +1, G = +2, G = +5, G = +10
100k
1M
FREQUENCY – Hz
100M
10M
Figure 12. Distortion vs. Frequency
5
–50
4
VOUT = 2V p-p
RL = 100⍀
3
DISTORTION – dBc
GAIN – dB
2
G = +1
RF = 0⍀
1
0
G = +2
RF = 402⍀
–1
–2
G = +10
RF = 909⍀
–3
–70
–80
2ND
–90
3RD
G = +5
RF = 1000⍀
–4
–5
0.3M
VOUT = 2V p-p
G = +2
RL = 1k⍀
–60
1M
10M
100M
FREQUENCY – Hz
–100
10k
1G
Figure 10. Large Signal Frequency Response,
G = +1, G = +2, G = +5, G = +10
1M
FREQUENCY – Hz
10M
100M
Figure 13. Distortion vs. Frequency
–40
0.5
VOUT = 100mV
G = +2
RL = 100⍀
RF = 402⍀
0.4
0.3
G = +2
RL = 1k⍀
–50
DISTORTION – dBc
0.2
OUTPUT – dB
100k
0.1
0
–0.1
–0.2
–0.3
–60
2ND
–70
3RD
–80
–0.4
–0.5
0.3M
–90
1M
10M
100M
FREQUENCY – Hz
1G
Figure 11. 0.1 dB Flatness
REV. B
0
0.4
0.8
1.2
1.6
2.0 2.4
VOUT – V p-p
2.8
3.2
3.6
Figure 14. Distortion vs. VOUT @ 20 MHz
–5–
4.0
AD8055/AD8056
10
10
G = +1
R L = 100⍀
RF = 0⍀
8
7
6
5
FALLTIME
4
3
2
RISETIME
1
0
0
0.5
1.0
1.5
2.0
2.5 3.0
VIN – V p-p
3.5
4.0
4.5
7
6
5
4
RISETIME
3
2
0
5.0
FALLTIME
0
0.2
0.4
0.6
0.8
1.0
VIN – V p-p
1.2
1.4
1.6
Figure 18. Risetime and Falltime vs. VIN
10
5.0
G = +1
R L = 1k⍀
RF = 0⍀
8
G = +2
RL = 1k⍀
RF = 402⍀
4.5
RISETIME AND FALLTIME – ns
9
RISETIME AND FALLTIME – ns
8
1
Figure 15. Risetime and Falltime vs. VIN
7
6
5
4
FALLTIME
3
2
RISETIME
1
4.0
3.5
RISETIME
3.0
2.5
2.0
FALLTIME
1.5
1.0
0.5
0
0
0.5
1.0
1.5
2.0
2.5
3.0
VIN – V p-p
3.5
4.0
4.5
0
5.0
0
0.2
0.4
0.6
0.8
1.0
VIN – V p-p
1.2
1.4
1.6
Figure 19. Risetime and Falltime vs. VIN
Figure 16. Risetime and Falltime vs. VIN
0.7
10
V OUT = 0V TO 2V OR
0V TO –2V
G = +2
R L = 100⍀
0.6
0.5
0.4
0
G = +2
RF = 402⍀
–10
–20
0.3
PSRR – dB
SETTLING TIME – %
G = +2
RL = 100⍀
RF = 402⍀
9
RISETIME AND FALLTIME – ns
RISETIME AND FALLTIME – ns
9
0.2
0.1
0
–0.1
–30
–PSRR
–40
–50
+PSRR
–60
–0.2
–70
–0.3
–80
–0.4
–0.5
0
10
20
30
TIME – ns
40
50
–90
0.1
60
1
10
FREQUENCY – MHz
100
500
Figure 20. PSRR vs. Frequency
Figure 17. Settling Time
–6–
REV. B
AD8055/AD8056
Figure 21. Overload Recovery
Figure 24. Overload Recovery
90
–20
CROSSTALK – dB
–40
80
RL = 100⍀
70
OPEN LOOP GAIN – dB
–30
VIN = 0dBm
G = +2
RL = 100⍀
RF = 402⍀
–50
–60
SIDE 2 DRIVEN
–70
–80
SIDE 1 DRIVEN
–90
–120
0.1
30
20
1
10
FREQUENCY – MHz
100
–10
0.01
200
Figure 22. Crosstalk (Output-to-Output) vs. Frequency
0.1
1
10
FREQUENCY – MHz
100
500
Figure 25. Open Loop Gain vs. Frequency
0
45
402⍀
402⍀
RL = 100⍀
50⍀
402⍀
0
58⍀
PHASE – Degrees
–30
CMRR – dB
40
0
–110
–20
50
10
–100
–10
60
402⍀
–40
–50
–60
–70
–45
–90
–135
–80
–90
–100
0.1
1
10
FREQUENCY – MHz
100
–180
0.01
500
Figure 23. CMRR vs. Frequency
REV. B
0.1
1
10
FREQUENCY – MHz
100
Figure 26. Phase vs. Frequency
–7–
500
1000
0.04
1 BACK TERMINATED LOAD (150⍀)
0.02
0.00
G = +2
RF = 402⍀
–0.02
–0.04
VOLTAGE NOISE – nV Hz
DIFFERENTIAL PHASE – DIFFERENTIAL GAIN – %
Degrees
AD8055/AD8056
1ST 2ND 3RD 4TH 5TH 6TH 7TH 8TH 9TH 10TH 11TH
IRE
0.04
1 BACK TERMINATED LOAD (150⍀)
0.02
100
0.00
G = +2
RF = 402⍀
–0.02
1
10
–0.04
1ST 2ND 3RD 4TH 5TH 6TH 7TH 8TH 9TH 10TH 11TH
IRE
Figure 27. Differential Gain and Differential Phase
DIFFERENTIAL GAIN – %
6nV/ Hz
10
1k
100
10k
100k
FREQUENCY – Hz
1M
10M
15M
Figure 30. Voltage Noise vs. Frequency
100
0.04
4 VIDEO LOADS (37.5⍀)
0.02
G = +2
RF = 402⍀
–0.02
DIFFERENTIAL PHASE –
Degrees
–0.04
0.15
VOLTAGE NOISE – pA Hz
0.00
1ST 2ND 3RD 4TH 5TH 6TH 7TH 8TH 9TH 10TH 11TH
IRE
4 VIDEO LOADS (37.5⍀)
0.10
0.05
10
1
0.00
–0.05
G = +2
RF = 402⍀
–0.10
–0.15
0.1
10
1ST 2ND 3RD 4TH 5TH 6TH 7TH 8TH 9TH 10TH 11TH
IRE
Figure 28. Differential Gain and Differential Phase
1M
10M
15M
45
VS = ⴞ5V
4.5
40
G = +2
RF = 402⍀
35
4.0
RL = 1k⍀
3.5
30
3.0
25
2.5
RL = 150⍀
2.0
| ZOUT | – ⍀
ⴞVOUT – Volts
10k
100k
FREQUENCY – Hz
Figure 31. Current Noise vs. Frequency
5.0
RL = 50⍀
20
15
1.5
10
1.0
5
0
0.5
0
–55
1k
100
–35
–15
25
45
65
5
TEMPERATURE – ⴗC
85
105
–5
0.01
125
0.1
1
10
FREQUENCY – MHz
100
500
Figure 32. Output Impedance vs. Frequency
Figure 29. Output Swing vs. Temperature
–8–
REV. B
AD8055/AD8056
APPLICATIONS
Four-Line Video Driver
The AD8055 is a useful low cost circuit for driving up to four
video lines. For such an application, the amplifier is configured
for a noninverting gain of 2 as shown in Figure 33. The input
video source is terminated in 75 Ω and applied to the high
impedance noninverting input.
The gain of this circuit from the input to Amp 1 output is RF/RI,
while the gain to the output of Amp 2 is –RF/RI. The circuit
thus creates a balanced differential output signal from a singleended input. The advantage of this circuit is that the gain can be
changed by changing a single resistor and still maintain the
balanced differential outputs.
RF
402⍀
Each output cable is connected to the op amp output via a 75 Ω
series back termination resistor for proper cable termination.
The terminating resistors at the other ends of the lines will
divide the output signal by two, which is compensated for by
the gain-of-two of the op amp stage.
+5V
0.1␮F
RI
402⍀
VIN
For a single load, the differential gain error of this circuit was
measured to be 0.01%, with a differential phase error of
0.02 degrees. The two load measurements were 0.02% and
0.03 degrees, respectively. For four loads, the differential gain
error is 0.02%, while the differential phase increases to 0.1
degrees.
3
10␮F
8
49.9⍀
AMP1
+VOUT
1
2
402⍀
402⍀
AD8056
402⍀
402⍀
75⍀
VOUT1
+5V
75⍀
402⍀
6
49.9⍀
AMP2
0.1␮F
402⍀
2
3
5
VOUT2
7
–VOUT
7
4
75⍀
75⍀
AD8055
VIN
10␮F
75⍀
0.1␮F
6
10␮F
–5V
4
75⍀
75⍀
0.1␮F
VOUT3
10␮F
Figure 34. Single-Ended to Differential Line Driver
75⍀
Low Noise, Low Power Preamp
–5V
75⍀
VOUT4
75⍀
Figure 33. Four-Line Video Driver
The AD8055 makes a good low cost, low noise, low power
preamp. A gain of 10 preamp can be made with a feedback
resistor of 909 ohms and a gain resistor of 100 ohms as shown
in Figure 35. The circuit has a –3 dB bandwidth of 20 MHz.
Single-Ended to Differential Line Driver
909⍀
Creating differential signals from single-ended signals is
required for driving balanced, twisted pair cables, differential
input A/D converters and other applications that require differential signals. This is sometimes accomplished by using an inverting
and a noninverting amplifier stage to create the complementary
signals.
The circuit shown in Figure 34 shows how an AD8056 can be
used to make a single-ended to differential converter that offers
some advantages over the architecture mentioned above. Each
op amp is configured for unity gain by the feedback resistors
from the outputs to the inverting inputs. In addition, each output drives the opposite op amp with a gain of –1 by means of the
crossed resistors. The result of this is that the outputs are complementary and there is high gain in the overall configuration.
Feedback techniques similar to a conventional op amp are used
to control the gain of the circuit. From the noninverting input
of Amp 1 to the output of Amp 2, is an inverting gain. Between
these points a feedback resistor can be used to close the loop.
As in the case of a conventional op amp inverting gain stage, an
input resistor is added to vary the gain.
REV. B
+5V
0.1␮F
100⍀
2
AD8055
3
+
10␮F
7
VOUT
6
4
RS
0.1␮F
10␮F
–5V
Figure 35. Low Noise, Low Power Preamp with G = 10
and BW = 20 MHz
With a low source resistance (<approximately 100 Ω), the major
contributors to the input referred noise of this circuit are the
input voltage noise of the amplifier and the noise of the 100 Ω
resistor. These are 6 nV/√Hz and 1.2 nV/√Hz, respectively.
These values yield a total input referred noise of 6.1 nV/√Hz.
–9–
AD8055/AD8056
Power Dissipation Limits
5
With a 10 V supply (total VCC – VEE), the quiescent power dissipation of the AD8055 in the SOT-23-5 package is 65 mW,
while the quiescent power dissipation of the AD8056 in the
microSOIC is 120 mW. This translates into a 15.6°C rise above
the ambient for the SOT-23-5 package and a 24°C rise for the
microSOIC package.
402⍀
4
402⍀
CL = 30pF
NORMALIZED GAIN – dB
3
The power dissipated under heavy load conditions is approximately equal to the supply voltage minus the output voltage,
times the load current, plus the quiescent power computed above.
This total power dissipation is then multiplied by the thermal
resistance of the package to find the temperature rise, above
ambient, of the part. The junction temperature should be kept
below 150°C.
CL
VIN = 0dBm
2
100⍀
50⍀
1
0
–1
CL = 20pF
–2
CL = 10pF
–3
CL = 0pF
–4
–5
0.3
The AD8055 in the SOT-23-5 package can dissipate 270 mW
while the AD8056 in the microSOIC package can dissipate
325 mW (at 85°C ambient) without exceeding the maximum
die temperature. In the case of the AD8056, this is greater than
1.5 V rms into 50 Ω, enough to accommodate a 4 V p-p sine-wave
signal on both outputs simultaneously. But since each output of
the AD8055 or AD8056 is capable of supplying as much as
110 mA into a short circuit, a continuous short circuit condition
will exceed the maximum safe junction temperature.
Resistor Selection
1
10
FREQUENCY – MHz
100
500
Figure 36. Capacitive Load Drive
In general, to minimize peaking or to ensure the stability for
larger values of capacitive loads, a small series resistor, RS, can
be added between the op amp output and the capacitor, CL. For
the setup depicted in Figure 37, the relationship between RS and
CL was empirically derived and is shown in Figure 38. RS was
chosen to produce less than 1 dB of peaking in the frequency
response. Note also that after a sharp rise RS quickly settles to
about 25 Ω.
The following table is provided as a guide to resistor selection
for maintaining gain flatness vs. frequency for various values of
gain.
402⍀
+5V
Gain
RF (⍀)
RI (⍀)
–3 dB
Bandwidth
(MHz)
+1
+2
+5
+10
0
402
1k
909
—
402
249
100
300
160
45
20
0.1␮F
402⍀
AD8055
VIN = 0dBm
10␮F
7
2
3
FET PROBE
VOUT
RS
6
CL
4
50⍀
0.1␮F
10␮F
–5V
Figure 37. Setup for RS vs. CL
Driving Capacitive Loads
40
35
30
25
RS – ⍀
When driving a capacitive load, most op amps will exhibit peaking in the frequency response just before the frequency rolls off.
Figure 36 shows the responses for an AD8056 running at a gain
of +2, with a 100 Ω load that is shunted by various values of
capacitance. It can be seen that under these conditions, the part
is still stable with capacitive loads of up to 30 pF.
20
15
10
5
0
0
10
20
30
40
CL – pF
50
60
270
Figure 38. RS vs. CL
–10–
REV. B
AD8055/AD8056
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead microSOIC Package
(RM-8)
0.430 (10.92)
0.348 (8.84)
8
0.122 (3.10)
0.114 (2.90)
5
0.280 (7.11)
0.240 (6.10)
1
8
0.100 (2.54)
BSC
0.210
(5.33)
MAX
0.060 (1.52)
0.015 (0.38)
1
0.022 (0.558) 0.070 (1.77) SEATING
0.014 (0.356) 0.045 (1.15) PLANE
0.120 (3.05)
0.112 (2.84)
0.043 (1.09)
0.037 (0.94)
0.018 (0.46)
SEATING 0.008 (0.20)
PLANE
4
0.2440 (6.20)
0.2284 (5.80)
0.0709 (1.800)
0.0590 (1.500)
0.028 (0.71)
0.016 (0.41)
0.0192 (0.49)
0.0138 (0.35)
4
1
2
3
0.1181 (3.000)
0.0984 (2.500)
0.0374 (0.950) REF
0.0688 (1.75)
0.0532 (1.35)
8ⴗ
0.0500 (1.27)
0.0098 (0.25) 0ⴗ
0.0160 (0.41)
0.0075 (0.19)
5
PIN 1
0.0196 (0.50)
ⴛ 45ⴗ
0.0099 (0.25)
0.0500 (1.27)
BSC
SEATING
PLANE
33ⴗ
27ⴗ
0.1220 (3.100)
0.1063 (2.700)
PIN 1
0.0098 (0.25)
0.0040 (0.10)
0.011 (0.28)
0.003 (0.08)
5-Lead Plastic Surface Mount
(RT-5)
0.1968 (5.00)
0.1890 (4.80)
1
0.120 (3.05)
0.112 (2.84)
0.006 (0.15)
0.002 (0.05)
0.015 (0.381)
0.008 (0.204)
8-Lead Small Outline SOIC
(SO-8)
5
4
PIN 1
0.0256 (0.65) BSC
0.195 (4.95)
0.115 (2.93)
0.130
(3.30)
MIN
8
0.199 (5.05)
0.187 (4.75)
0.325 (8.25)
0.300 (7.62)
0.160 (4.06)
0.115 (2.93)
5
0.122 (3.10)
0.114 (2.90)
4
PIN 1
0.1574 (4.00)
0.1497 (3.80)
C3045a–0–6/00 (rev. B) 01063
8-Lead Plastic DIP
(N-8)
0.0748 (1.900)
REF
0.0512 (1.300)
0.0354 (0.900)
0.0197 (0.500) SEATING
PLANE
0.0118 (0.300)
10ⴗ
0ⴗ
0.0236 (0.600)
0.0039 (0.100)
PRINTED IN U.S.A.
0.0059 (0.150)
0.0000 (0.000)
0.0079 (0.200)
0.0035 (0.090)
0.0571 (1.450)
0.0354 (0.900)
REV. B
–11–