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AD8038

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AD8038
Low Power 350 MHz
Voltage Feedback Amplifiers
AD8038/AD8039
FEATURES
Low Power
1 mA Supply Current/Amp
High Speed
350 MHz, –3 dB Bandwidth (G = +1)
425 V/␮s Slew Rate
Low Cost
Low Noise
8 nV/√Hz @ 100 kHz
600 fA/√Hz @ 100 kHz
Low Input Bias Current: 750 nA Max
Low Distortion
–90 dB SFDR @ 1 MHz
–65 dB SFDR @ 5 MHz
Wide Supply Range: 3 V to 12 V
Small Packaging: SOT-23-8, SC70-5, and SOIC-8
APPLICATIONS
Battery-Powered Instrumentation
Filters
A/D Drivers
Level Shifting
Buffering
High Density PC Boards
Photo Multipliers
CONNECTION DIAGRAMS
SC70-5 (KS)
SOIC-8 (R)
AD8038
8
DISABLE
–IN 2
7
+VS
+IN 3
6
VOUT
NC 1
–VS 4
5
AD8038
VOUT 1
–VS 2
+ –
4 –IN
+IN 3
NC
5 +VS
NC = NO CONNECT
SOIC-8 (R) and SOT-23-8 (RT)
AD8039
VOUT1 1
8
+VS
–IN1 2
7
VOUT2
+IN1 3
6
–IN2
–VS 4
5
+IN2
capacitive loads up to 15 pF. If driving larger capacitive loads,
a small series resistor is needed to avoid excessive peaking or
overshoot.
www.BDTIC.com/ADI
The AD8038 (single) and AD8039 (dual) amplifiers are high
speed (350 MHz) voltage feedback amplifiers with an exceptionally low quiescent current of 1.0 mA/amplifier typical (1.5 mA max).
The AD8038 single amplifier in the SOIC-8 package has a disable feature. Despite being low power and low cost, the amplifier
provides excellent overall performance. Additionally, it offers
a high slew rate of 425 V/µs and low input offset voltage of
3 mV max.
ADI’s proprietary XFCB process allows low noise operation
(8 nV/√Hz and 600 fA/√Hz) at extremely low quiescent currents.
Given a wide supply voltage range (3 V to 12 V), wide bandwidth, and small packaging, the AD8038 and AD8039 amplifiers
are designed to work in a variety of applications where power and
space are at a premium.
The AD8038 and AD8039 amplifiers have a wide input commonmode range of 1 V from either rail and will swing within 1 V of
each rail on the output. These amplifiers are optimized for driving
24
21
G = +10
18
15
GAIN – dB
PRODUCT DESCRIPTION
The AD8039 amplifier is the only dual, low power, high speed
amplifier available in a tiny SOT-23-8 package, and the single
AD8038 is available in both a SOIC-8 and an SC70-5 package.
These amps are rated to work over the industrial temperature
range of –40°C to +85°C.
G = +5
12
9
G = +2
6
3
G = +1
0
–3
–6
0.1
1
10
FREQUENCY – MHz
100
1000
Figure 1. Small Signal Frequency Response for
Various Gains, VOUT = 500 mV p-p, VS = ± 5 V
REV. F
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 that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703
© 2004 Analog Devices, Inc. All rights reserved.
AD8038/AD8039–SPECIFICATIONS (T = 25ⴗC, V = ⴞ5 V, R = 2 k⍀, Gain = +1, unless otherwise noted.)
A
Parameter
DYNAMIC PERFORMANCE
–3 dB Bandwidth
Bandwidth for 0.1 dB Flatness
Slew Rate
Overdrive Recovery Time
Settling Time to 0.1%
NOISE/HARMONIC PERFORMANCE
SFDR
Second Harmonic
Third Harmonic
Second Harmonic
Third Harmonic
Crosstalk, Output-to-Output (AD8039)
Input Voltage Noise
Input Current Noise
DC PERFORMANCE
Input Offset Voltage
Input Offset Voltage Drift
Input Bias Current
Input Bias Current Drift
Input Offset Current
Open-Loop Gain
S
L
Conditions
Min
Typ
G = +1, VO = 0.5 V p-p
G = +2, VO = 0.5 V p-p
G = +1, VO = 2 V p-p
G = +2, VO = 0.2 V p-p
G = +1, VO = 2 V Step, RL = 2 kΩ
G = +2, 1 V Overdrive
G = +2, VO = 2 V Step
300
350
175
100
45
425
50
18
MHz
MHz
MHz
MHz
V/µs
ns
ns
fC = 1 MHz, VO = 2 V p-p, RL = 2 kΩ
fC = 1 MHz, VO = 2 V p-p, RL = 2 kΩ
fC = 5 MHz, VO = 2 V p-p, RL = 2 kΩ
fC = 5 MHz, VO = 2 V p-p, RL = 2 kΩ
f = 5 MHz, G = +2
f = 100 kHz
f = 100 kHz
–90
–92
–65
–70
–70
8
600
dBc
dBc
dBc
dBc
dB
nV/√Hz
fA/√Hz
VO = ± 2.5 V
0.5
4.5
400
3
25
70
400
Max
3
750
Unit
mV
µV/°C
nA
nA/°C
± nA
dB
www.BDTIC.com/ADI
INPUT CHARACTERISTICS
Input Resistance
Input Capacitance
Input Common-Mode Voltage Range
Common-Mode Rejection Ratio
RL = 1 kΩ
VCM = ± 2.5 V
OUTPUT CHARACTERISTICS
DC Output Voltage Swing
Capacitive Load Drive
RL = 2 kΩ, Saturated Output
30% Overshoot, G = +2
POWER SUPPLY
Operating Range
Quiescent Current per Amplifier
Power Supply Rejection Ratio
POWER-DOWN DISABLE*
Turn-On Time
Turn-Off Time
Disable Voltage—Part is OFF
Disable Voltage—Part is ON
Disabled Quiescent Current
Disabled In/Out Isolation
61
10
2
±4
67
MΩ
pF
V
dB
±4
20
V
pF
3.0
– Supply
+ Supply
–71
–64
1.0
–77
–70
180
700
+VS – 4.5
+VS – 2.5
0.2
–60
f = 1 MHz
12
1.5
V
mA
dB
dB
ns
ns
V
V
mA
dB
*Only available in AD8038 SOIC-8 package.
Specifications subject to change without notice.
–2–
REV. F
AD8038/AD8039
SPECIFICATIONS (T = 25ⴗC, V = 5 V, R = 2 k⍀ to V /2, Gain = +1, unless otherwise noted.)
A
S
Parameter
DYNAMIC PERFORMANCE
–3 dB Bandwidth
Bandwidth for 0.1 dB Flatness
Slew Rate
Overdrive Recovery Time
Settling Time to 0.1%
NOISE/HARMONIC PERFORMANCE
SFDR
Second Harmonic
Third Harmonic
Second Harmonic
Third Harmonic
Crosstalk, Output-to-Output
Input Voltage Noise
Input Current Noise
DC PERFORMANCE
Input Offset Voltage
Input Offset Voltage Drift
Input Bias Current
Input Bias Current Drift
Input Offset Current
Open-Loop Gain
L
S
Conditions
Min
Typ
G = +1, VO = 0.2 V p-p
G = +2, VO = 0.2 V p-p
G = +1, VO = 2 V p-p
G = +2, VO = 0.2 V p-p
G = +1, VO = 2 V Step, RL = 2 kΩ
G = +2, 1 V Overdrive
G = +2, VO = 2 V Step
275
300
150
30
45
365
50
18
MHz
MHz
MHz
MHz
V/µs
ns
ns
–82
–79
–60
–67
–70
8
600
dBc
dBc
dBc
dBc
dB
nV/√Hz
fA/√Hz
340
fC = 1 MHz, VO = 2 V p-p, RL = 2 kΩ
fC = 1 MHz, VO = 2 V p-p, RL = 2 kΩ
fC = 5 MHz, VO = 2 V p-p, RL = 2 kΩ
fC = 5 MHz, VO = 2 V p-p, RL = 2 kΩ
f = 5 MHz, G = +2
f = 100 kHz
f = 100 kHz
Max
3
Unit
VO = ± 2.5 V
0.8
3
400
3
30
70
INPUT CHARACTERISTICS
Input Resistance
Input Capacitance
Input Common-Mode Voltage Range
Common-Mode Rejection Ratio
RL = 1 kΩ
VCM = ± 1 V
10
2
1.0–4.0
65
MΩ
pF
V
dB
OUTPUT CHARACTERISTICS
DC Output Voltage Swing
Capacitive Load Drive
RL = 2 kΩ, Saturated Output
30% Overshoot
0.9–4.1
20
V
pF
750
www.BDTIC.com/ADI
59
POWER SUPPLY
Operating Range
Quiescent Current per Amplifier
Power Supply Rejection Ratio
POWER-DOWN DISABLE*
Turn-On Time
Turn-Off Time
Disable Voltage—Part is OFF
Disable Voltage—Part is ON
Disabled Quiescent Current
Disabled In/Out Isolation
3
–65
210
700
+VS – 4.5
+VS – 2.5
0.2
–60
f = 1 MHz
*Only available in AD8038 SOIC-8 package.
Specifications subject to change without notice.
REV. F
0.9
–71
–3–
12
1.5
mV
µV/°C
nA
nA/°C
± nA
dB
V
mA
dB
ns
ns
V
V
mA
dB
AD8038/AD8039
2.0
MAXIMUM POWER DISSIPATION – W
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.6 V
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . See Figure 2
Common-Mode Input Voltage . . . . . . . . . . . . . . . . . . . . . . . ± VS
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . ± 4 V
Storage Temperature . . . . . . . . . . . . . . . . . . . . –65°C to +125°C
Operating Temperature Range . . . . . . . . . . . . . –40°C to +85°C
Lead Temperature Range (Soldering 10 sec) . . . . . . . . . . . 300°C
*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.
MAXIMUM POWER DISSIPATION
The maximum safe power dissipation in the AD8038/AD8039
package is limited by the associated rise in junction temperature
(TJ) on the die. The plastic encapsulating the die will locally reach
the junction temperature. At approximately 150°C, which is the
glass transition temperature, the plastic will change its properties.
Even temporarily exceeding this temperature limit may change the
stresses that the package exerts on the die, permanently shifting the
parametric performance of the AD8038/AD8039. Exceeding a
junction temperature of 175°C for an extended period of time can
result in changes in the silicon devices, potentially causing failure.
1.5
SOIC-8
SOT-23-8
1.0
SC70-5
0.5
0
–55
–25
5
35
65
95
AMBIENT TEMPERATURE – ⴗC
125
Figure 2. Maximum Power Dissipation vs.
Temperature for a 4-Layer Board
RMS output voltages should be considered. If RL is referenced to VS–, as
in single-supply operation, then the total drive power is V S ⫻ IOUT.
If the rms signal levels are indeterminate, consider the worst case,
when VOUT = VS /4 for RL to midsupply:
PD = (VS × IS ) + (VS / 4 ) / RL
2
The still-air thermal properties of the package and PCB (␪JA),
ambient temperature (TA), and total power dissipated in the package
(PD) determine the junction temperature of the die. The junction
temperature can be calculated as follows:
In single-supply operation with RL referenced to VS–, worst case is
VOUT = VS /2.
Airflow will increase heat dissipation, effectively reducing ␪JA. Also,
more metal directly in contact with the package leads from metal
traces, through-holes, ground, and power planes will reduce the ␪JA.
Care must be taken to minimize parasitic capacitances at the input
leads of high speed op amps as discussed in the board layout section.
www.BDTIC.com/ADI
TJ = TA + (PD × θ JA )
The power dissipated in the package (PD) is the sum of the quiescent
power dissipation and the power dissipated in the package due to the
load drive for all outputs. The quiescent power is the voltage between
the supply pins (VS) multiplied by the quiescent current (IS). Assuming the load (RL) is referenced to midsupply, then the total drive power
is VS /2 ⫻ IOUT, some of which is dissipated in the package and some
in the load (VOUT ⫻ IOUT). The difference between the total drive
power and the load power is the drive power dissipated in the package.
PD = quiescent power + (total drive power – load power)
[
]
[
PD = [VS × IS ] + (VS / 2) × (VOUT /RL ) – VOUT /RL
2
Figure 2 shows the maximum safe power dissipation in the package
versus the ambient temperature for the SOIC-8 (125°C/W), SC70-5
(210°C/W), and SOT-23-8 (160°C/W) package on a JEDEC standard
4-layer board. ␪JA values are approximations.
OUTPUT SHORT CIRCUIT
Shorting the output to ground or drawing excessive current from
the AD8038/AD8039 will likely cause a catastrophic failure.
]
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Outline
AD8038AR
AD8038AR-REEL
AD8038AR-REEL7
AD8038AKS-R2
AD8038AKS-REEL
AD8038AKS-REEL7
AD8039AR
AD8039AR-REEL
AD8039AR-REEL7
AD8039ART-R2
AD8039ART-REEL
AD8039ART-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
–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
8-Lead SOIC
8-Lead SOIC
5-Lead SC70
5-Lead SC70
5-Lead SC70
8-Lead SOIC
8-Lead SOIC
8-Lead SOIC
8-Lead SOT-23
8-Lead SOT-23
8-Lead SOT-23
R-8
R-8
R-8
KS-5
KS-5
KS-5
R-8
R-8
R-8
RT-8
RT-8
RT-8
Branding Information
HUA
HUA
HUA
HYA
HYA
HYA
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 AD8038/AD8039 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.
–4–
REV. F
Typical Performance Characteristics–AD8038/AD8039
(Default Conditions: ⴞ5 V, CL = 5 pF, G = ⴙ2, RG = RF = 1 k⍀, RL = 2 k⍀, VO = 2 V p-p, Frequency = 1 MHz, TA = 25ⴗC.)
7
7
24
VS = ⴞ1.5V
G = +10
21
6
G = +5
5
9
G = +2
6
3
G = +1
0
–3
–6
0.1
1
10
100
FREQUENCY – MHz
TPC 1. Small Signal Frequency
Response for Various Gains,
VOUT = 500 mV p-p
3
1
1
1
10
100
FREQUENCY – MHz
0
0.1
1000
4
1
10
100
FREQUENCY – MHz
1000
RL = 2k⍀
7
6
RL = 500⍀
5
GAIN – dB
GAIN – dB
RL = 500⍀
RL = 1k⍀
8
6
5
RL = 500⍀
TPC 3. Small Signal Frequency
Response for Various RLOAD,
VS = ± 5 V, VOUT = 500 mV p-p
RL = 2k⍀
7
6
3
2
8
RL = 2k⍀
4
2
TPC 2. Small Signal Frequency
Response for Various Supplies,
VOUT = 500 mV p-p
7
GAIN – dB
4
0
0.1
1000
5
VS = ⴞ5V
GAIN – dB
12
GAIN – dB
GAIN – dB
15
RL = 2k⍀
6
VS = ⴞ2.5V
18
RL = 500⍀
5
www.BDTIC.com/ADI
RL = 1k⍀
3
2
1
0
0.1
1
10
100
FREQUENCY – MHz
4
3
RL = 1k⍀
TPC 4. Small Signal Frequency
Response for Various RLOAD,
VS = 5 V, VOUT = 500 mV p-p
2
1
1
1
10
FREQUENCY – MHz
100
2
VOUT = 200mV
CL = 15pF
1
VOUT = 1V
5
CL = 10pF
3
1
10
FREQUENCY – MHz
TPC 6. Large Signal Frequency
Response for Various RLOAD,
VOUT = 4 V p-p, VS = ± 5 V
7
CL = 15pF
4
RL = 1k⍀
0
0.1
100
TPC 5. Large Signal Frequency
Response for Various RLOAD,
VOUT = 3 V p-p, VS = 5 V
5
3
2
0
0.1
1000
4
0
3
0
–1
CL = 5pF
CL = 10pF
1
–1
–2
GAIN – dB
1
GAIN – dB
GAIN – dB
2
–1
–2
VOUT = 500mV
–3
CL = 5pF
VOUT = 2V
–4
–3
–3
–5
–4
–5
–5
1
10
100
FREQUENCY – MHz
1000
TPC 7. Small Signal Frequency
Response for Various CLOAD,
V OUT = 500 mV p-p, V S = ± 5 V,
G = +1
REV. F
1
10
100
FREQUENCY – MHz
1000
TPC 8. Small Signal Frequency
Response for Various CLOAD,
VOUT = 500 mV p-p, VS = 5 V,
G = +1
–5–
–6
0.1
1
10
100
FREQUENCY – MHz
1000
TPC 9. Frequency Response for
Various Output Voltage Levels
AD8038/AD8039
80
180
9
–50
70
6
PHASE
90
40
30
GAIN
20
45
10
GAIN – dB
50
PHASE – Degrees
OPEN-LOOP GAIN – dB
HARMONIC DISTORTION – dBc
135
60
–40ⴗC
+25ⴗC
3
+85ⴗC
0
0
0
–10
–20
0.01
0.1
1
10
100
FREQUENCY – MHz
–45
1000
–3
0.1
TPC 10. Open-Loop Gain and
Phase, VS = ± 5 V
RL = 500⍀ HD3
–60
–65
–70
RL = 2k⍀ HD3
–75
RL = 2k⍀ HD2
–80
–85
1
2
3
–65
–70
–75
RL = 2k⍀ HD3
RL = 2k⍀ HD2
–80
–85
1000
1
2
3
9
G = +1 HD2
G = +2 HD2
–60
–70
G = +2 HD3
–80
–90
–100
10
TPC 13. Harmonic Distortion vs.
Frequency for Various Loads,
VS = 5 V, VOUT = 2 V p-p, G = +2
G = +1 HD3
1
2
3
8
4
5
6
7
FREQUENCY – MHz
9
G = +2 HD2
–60
–70
G = +2 HD3
–80
G = +1 HD3
–90
–100
10
TPC 14. Harmonic Distortion vs.
Frequency for Various Gains,
VS = ± 5 V, VOUT = 2 V p-p
–40
10
–50
www.BDTIC.com/ADI
8
4
5
6
7
FREQUENCY – MHz
9
8
4
5
6
7
FREQUENCY – MHz
TPC 12. Harmonic Distortion vs.
Frequency for Various Loads,
VS = ± 5 V, VOUT = 2 V p-p, G = +2
HARMONIC DISTORTION – dBc
–55
–60
G = +1 HD2
HARMONIC DISTORTION – dBc
HARMONIC DISTORTION – dBc
10
100
FREQUENCY – MHz
–50
RL = 500⍀ HD2
–50
RL = 500⍀ HD3
–90
1
TPC 11. Frequency Response
vs. Temperature, Gain = +2,
VS = ± 5 V, VOUT = 2 V p-p
–45
–90
RL = 500⍀ HD2
–55
1
2
3
8
4
5
6
7
FREQUENCY – MHz
9
10
TPC 15. Harmonic Distortion vs.
Frequency for Various Gains,
VS = 5 V, VOUT = 2 V p-p
1000
–45
–50
5MHz HD2
10MHz HD3
–60
5MHz HD3
–70
1MHz HD3
–80
1MHz HD2
–90
–100
1
2
3
AMPLITUDE – V p-p
TPC 16. Harmonic Distortion vs.
VOUT Amplitude for Various
Frequencies, VS = ± 5 V, G = +2
4
–55
10MHz HD3
VOLTAGE NOISE – nV/ Hz
10MHz HD2
HARMONIC DISTORTION – dBc
HARMONIC DISTORTION – dBc
10MHz HD2
5MHz HD2
5MHz HD3
–65
–75
–85
–95
1.0
1MHz HD3
1MHz HD2
1.5
2.0
2.5
AMPLITUDE – V p-p
3.0
TPC 17. Harmonic Distortion vs.
Amplitude for Various Frequencies,
VS = 5 V, G = +2
–6–
100
10
1
10
100
1k
10k
100k
1M
10M 100M
FREQUENCY – Hz
TPC 18. Input Voltage Noise vs.
Frequency
REV. F
AD8038/AD8039
100000
RL = 2k⍀
NOISE – fA/ Hz
RL = 500⍀
RL = 500⍀
RL = 2k⍀
10000
1000
50mV/DIV
100
10
100
1000
10000 100000
FREQUENCY – Hz
TPC 19. Input Current Noise vs.
Frequency
5ns/DIV
50mV/DIV
5ns/DIV
1M
TPC 20. Small Signal Transient
Response for Various RLOAD,
VS = 5 V
CL = 25pF WITH
RSNUB = 19.6⍀
CL = 25pF WITH
RSNUB = 19.6⍀
TPC 21. Small Signal Transient
Response for Various RLOAD,
VS = ± 5 V
RL = 500⍀
RL = 2k⍀
2.5V
CL = 5pF
CL = 5pF
CL = 10pF
CL = 10pF
www.BDTIC.com/ADI
500mV/DIV
50mV/DIV
5ns/DIV
TPC 22. Small Signal Transient
Response for Various Capacitive
Loads, VS = 5 V
50mV/DIV
5ns/DIV
5ns/DIV
TPC 23. Small Signal Transient
Response for Various Capacitive
Loads, VS = ± 5 V
TPC 24. Large Signal Transient
Response for Various RLOAD,
VS = 5 V
CL = 10pF
RL = 500⍀
RL = 2k⍀
CL = 25pF
CL = 5pF
2.5V
1V/DIV
CL = 5pF
5ns/DIV
500mV/DIV
TPC 25. Large Signal Transient
Response for Various RLOAD,
VS = ± 5 V
REV. F
5ns/DIV
TPC 26. Large Signal Transient
Response for Various Capacitive
Loads, VS = 5 V
–7–
500mV/DIV
5ns/DIV
TPC 27. Large Signal Transient
Response for Various Capacitive
Loads, VS = ± 5 V
AD8038/AD8039
VS = ⴞ5V
G = +2
VOUT = 2V p-p
2mV/DIV
IN
IN
OUT
ERROR
VOLTAGE
+0.1%
0
OUT
2V/DIV
INPUT 1V/DIV
OUTPUT 2V/DIV
50ns/DIV
TPC 28. Input Overdrive
Recovery, Gain = +1
0.5V/DIV
5ns/DIV
TPC 30. 0.1% Settling Time
VOUT = 2 V p-p
–10
–20
VIN
50ns/DIV
TPC 29. Output Overdrive
Recovery, Gain = +2
–10
1000
–20
–30
100
–50
SIDE B
–60
–70
IMPEDANCE – ⍀
–30
–40
CMRR – dB
CROSSTALK – dB
t=0
–0.1%
VS = +5V
–40
–50
VS = ⴞ5V
SIDE A
–60
10
1
–80
VS = ⴞ5V
–70
–90
www.BDTIC.com/ADI
VS = +5V
–100
0.1
1
10
100
FREQUENCY – MHz
1000
–80
1
100
1000
0.1
FREQUENCY – MHz
TPC 31. AD8039 Crosstalk,
VIN = 1 V p-p, Gain = +1
1
10
100
FREQUENCY – MHz
TPC 32. CMRR vs. Frequency,
VIN = 1 V p-p
TPC 33. Output Impedance vs.
Frequency
10
9
1.25
0
8
–10
7
6
VOUT – p-p
–PSRR
–30
–40
+PSRR
–50
5
4
VS = +5V
3
–60
2
–70
1.00
0.75
0.50
0.25
1
–80
–90
0.01
1000
VS = ⴞ5V
SUPPLY CURRENT – mA
–20
PSRR – dB
10
0.1
0.01
0
0.1
1
10
100
FREQUENCY – MHz
TPC 34. PSRR vs. Frequency
1000
0
100
200
300
RLOAD – ⍀
400
TPC 35. Output Swing vs.
Load Resistance
–8–
500
0
0
2
4
6
8
SUPPLY VOLTAGE – V
10
12
TPC 36. AD8038 Supply
Current vs. Supply Voltage
REV. F
AD8038/AD8039
0
Input Capacitance
Along with bypassing and ground, high speed amplifiers can be
sensitive to parasitic capacitance between the inputs and ground.
A few pF of capacitance will reduce the input impedance at high
frequencies, in turn increasing the amplifiers’ gain, causing peaking of the frequency response, or even oscillations if severe enough.
It is recommended that the external passive components that
are connected to the input pins be placed as close as possible to
the inputs to avoid parasitic capacitance. The ground and power
planes must be kept at a distance of at least 0.05 mm from the
input pins on all layers of the board.
–10
ISOLATION – dB
–20
–30
–40
–50
–60
–70
–80
–90
0.1
1.0
10
100
FREQUENCY – MHz
1000
TPC 37. AD8038 Input-Output Isolation (G = +2,
R L = 2 k Ω , VS = ± 5 V
LAYOUT, GROUNDING, AND BYPASSING
CONSIDERATIONS
Disable
The AD8038 in the SOIC-8 package provides a disable feature.
This feature disables the input from the output (see TPC 37 for
input-output isolation) and reduces the quiescent current from
typically 1 mA to 0.2 mA. When the DISABLE node is pulled
below 4.5 V from the positive supply rail, the part becomes
disabled. In order to enable the part, the DISABLE node needs
to be pulled up to above 2.5 V below the positive rail.
Output Capacitance
To a lesser extent, parasitic capacitances on the output can cause
peaking of the frequency response. There are two methods to
minimize this effect.
1. Put a small value resistor in series with the output to isolate
the load capacitor from the amp’s output stage; see TPCs 7,
8, 22, and 23.
2. Increase the phase margin with higher noise gains or add a pole
with a parallel resistor and capacitor from –IN to the output.
Input-to-Output Coupling
The input and output signal traces should not be parallel to
minimize capacitive coupling between the inputs and outputs,
avoiding any positive feedback.
APPLICATIONS
Low Power ADC Driver
www.BDTIC.com/ADI
Power Supply Bypassing
1k⍀
Power supply pins are actually inputs, and care must be taken
so that a noise-free stable dc voltage is applied. The purpose of
bypass capacitors is to create low impedances from the supply to
ground at all frequencies, thereby shunting or filtering a majority
of the noise.
Decoupling schemes are designed to minimize the bypassing
impedance at all frequencies with a parallel combination of capacitors. 0.01 µF or 0.001 µF (X7R or NPO) chip capacitors are
critical and should be as close as possible to the amplifier package. Larger chip capacitors, such as the 0.1 µF capacitor, can be
shared among a few closely spaced active components in the same
signal path. A 10 µF tantalum capacitor is less critical for high
frequency bypassing and, in most cases, only one per board is
needed at the supply inputs.
+5V
0.1␮F
2.5V
10␮F
3V
0.1␮F
1k⍀
3
10␮F
8
REF
50⍀
1
VIN
VINA
2
0V
1k⍀
1k⍀
AD9203
AD8039
1k⍀
1k⍀
6
7
5
VINB
50⍀
4
1k⍀
0.1␮F
10␮F
Grounding
A ground plane layer is important in densely packed PC boards to
spread the current minimizing parasitic inductances. However,
an understanding of where the current flows in a circuit is critical
to implementing effective high speed circuit design. The length
of the current path is directly proportional to the magnitude of
parasitic inductances, and thus the high frequency impedance of
the path. High speed currents in an inductive ground return will
create an unwanted voltage noise.
–5V
1k⍀
Figure 3. Schematic to Drive AD9203 with the AD8039
Differential A/D Driver
The AD9203 is a low power (125 mW on a 5 V supply) 40 MSPS
10-bit converter. This represents a breakthrough in power/speed
for ADCs. As such, the low power, high performance AD8039
is an appropriate choice of amplifier to drive it.
The length of the high frequency bypass capacitor leads are most
In low supply voltage applications, differential analog inputs
critical. A parasitic inductance in the bypass grounding will work
are needed to increase the dynamic range of the ADC inputs.
against the low impedance created by the bypass capacitor. Place
Differential driving can also reduce second and other even-order
the ground leads of the bypass capacitors at the same physical
distortion products. The AD8039 can be used to make a
location. Because load currents flow from the supplies as well, the
dc-coupled, single-ended-to-differential driver for one of these
ground for the load impedance should be at the same physical
ADCs. Figure 3 is a schematic of such a circuit for driving an
location as the bypass capacitor grounds. For the larger value
AD9203, a 10-bit, 40 MSPS ADC.
capacitors, which are intended to be effective at lower frequencies,
the current return path distance is less critical.
–9–
REV. F
AD8038/AD8039
The AD9203 works best when the common-mode voltage at the
input is at the midsupply or 2.5 V. The output stage design of
the AD8039 makes it ideal for driving these types of ADCs.
In this circuit, one of the op amps is configured in the inverting
mode, while the other is in the noninverting mode. However, to
provide better bandwidth matching, each op amp is configured
for a noise gain of +2. The inverting op amp is configured for a
gain of –1, while the noninverting op amp is configured for a
gain of +2. Each has a very similar ac response. The input signal
to the noninverting op amp is divided by 2 to normalize its
voltage level and make it equal to the inverting output.
The outputs of the op amps are centered at 2.5 V, which is the
midsupply level of the ADC. This is accomplished by first taking
the 2.5 V reference output of the ADC and dividing it by 2 with
a pair of 1 kΩ resistors. The resulting 1.25 V is applied to each
op amp’s positive input. This voltage is then multiplied by the
gain of the op amps to provide a 2.5 V level at each output.
RF
1⍀
680pF
+2.5V
10␮F
0.1␮F
R1
200⍀
VIN
R4
49.9⍀
R2
499⍀
R3
49.9⍀
C1
100pF
AD8038
VOUT
R5
75⍀
C3
33pF
–2.5V
0.1␮F
10␮F
Figure 4. Low-Pass Filter for Video
Figure 5 shows the frequency response of this filter. The response
is down 3 dB at 6 MHz, so it passes the video band with little
attenuation. The rejection at 27 MHz is 45 dB, which provides
more than a factor of 100 in suppression of the clock components
at this frequency.
10
Low Power Active Video Filter
Some composite video signals derived from a digital source
contain clock feedthrough that can limit picture quality. Active
filters made from op amps can be used in this application, but
they will consume 25 mW to 30 mW for each channel. In
power-sensitive applications, this can be too much, requiring
the use of passive filters that can create impedance matching
problems when driving any significant load.
0
GAIN – dB
–10
The AD8038 can be used to make an effective low-pass active
filter that consumes one-fifth of the power consumed by an
active filter made from an op amp. Figure 4 shows a circuit that
uses an AD8038 to create a single ± 2.5 V supply, three-pole
Sallen-Key filter. This circuit uses a single RC pole in front of a
standard two-pole active section.
–20
–30
–40
www.BDTIC.com/ADI
–50
–60
0.1
1
10
FREQUENCY – MHz
100
Figure 5. Video Filter Response
–10–
REV. F
AD8038/AD8039
OUTLINE DIMENSIONS
8-Lead Standard Small Outline Package [SOIC]
(R-8)
8-Lead Small Outline Transistor Package [SOT-23]
(RT-8)
Dimensions shown in millimeters and (inches)
Dimensions shown in millimeters
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
8
5
1
4
1.27 (0.0500)
BSC
0.25 (0.0098)
0.10 (0.0040)
COPLANARITY
SEATING
0.10
PLANE
2.90 BSC
6.20 (0.2440)
5.80 (0.2284)
7
6
5
1
2
3
4
2.80 BSC
PIN 1
INDICATOR
0.50 (0.0196)
ⴛ 45ⴗ
0.25 (0.0099)
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
0.31 (0.0122)
8
1.60 BSC
0.65 BSC
1.95
BSC
1.30
1.15
0.90
8ⴗ
0.25 (0.0098) 0ⴗ 1.27 (0.0500)
0.40 (0.0157)
0.17 (0.0067)
1.45 MAX
COMPLIANT TO JEDEC STANDARDS MS-012AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
0.15 MAX
0.38
0.22
SEATING
PLANE
0.22
0.08
8ⴗ
4ⴗ
0ⴗ
COMPLIANT TO JEDEC STANDARDS MO-178BA
www.BDTIC.com/ADI
5-Lead Thin Shrink Small Outline Transistor Package [SC70]
(KS-5)
Dimensions shown in millimeters
2.00 BSC
4
5
1.25 BSC
2.10 BSC
1
2
3
PIN 1
0.65 BSC
1.00
0.90
0.70
0.10 MAX
1.10 MAX
0.22
0.08
0.30
0.15
0.10 COPLANARITY
SEATING
PLANE
COMPLIANT TO JEDEC STANDARDS MO-203AA
REV. F
–11–
0.46
0.36
0.26
0.60
0.45
0.30
AD8038/AD8039
Revision History
Location
Page
8/04–Data Sheet Changed from REV. E to REV. F.
8/03–Data Sheet Changed from REV. D to REV. E.
Change to TPC 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7/03–Data Sheet Changed from REV. C to REV. D.
Changes to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Updated TPC 35 Caption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6/03–Data Sheet Changed from REV. B to REV. C.
Updated CONNECTION DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Updated ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5/02–Data Sheet Changed from REV. A to REV. B.
Add part number AD8038 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UNIVERSAL
Changes to Product Title . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Changes to FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Changes to PRODUCT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Changes to CONNECTION DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Update to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
www.BDTIC.com/ADI
Update to MAXIMUM POWER DISSIPATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Update to OUTPUT SHORT CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Update to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Change to FIGURE 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Change to TPC 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Change to TPC 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Change to TPC 27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Change to TPC 29 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Change to TPC 30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Change to TPC 31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Added TPC 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Added TPC 37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Edits to Low Power Active Video Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Change to Figure 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4/02–Data Sheet Changed from REV. 0 to REV. A.
Changes to FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Update SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2, 3
Edits to TPC 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
–12–
REV. F
C02951–0–8/04(F)
Changes to Figure 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Fly UP