ANALOG DEVICES AD8137 Service Manual
Low Cost, Low Power 12-Bit
www.BDTIC.com/ADI
FEATURES
Fully differential
Extremely low power with power-down feature
2.6 mA quiescent supply current @ 5 V
450 µA in power-down mode @ 5 V
High speed
110 MHz large signal 3 dB bandwidth @ G = 1
450 V/µs slew rate
12-bit SFDR performance @ 500 kHz
Fast settling time: 100 ns to 0.02%
Low input offset voltage: ±2.6 mV max
Low input offset current: 0.45 µA max
Differential input and output
Differential-to-differential or single-ended-to-differential
operation
Rail-to-rail output
Adjustable output common-mode voltage
Externally adjustable gain
Wide supply voltage range: 2.7 V to 12 V
Available in small SOIC package
APPLICATIONS
12-bit ADC drivers
Portable instrumentation
Battery-powered applications
Single-ended-to-differential converters
Differential active filters
Video amplifiers
Level shifters
Differential ADC Driver
AD8137
FUNCTIONAL BLOCK DIAGRAM
AD8137
–IN
1
2
V
OCM
V
3
S+
+OUT
4
Figure 1.
3
2
1
0
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
RG= 1kΩ
NORMALIZED CLOSED-LOOP GAIN (dB)
V
–11
–12
= 0.1V p-p
O, dm
0.1 1 10 100 1000
Figure 2. Small Signal Response for Various Gains
G = 10
FREQUENCY (MHz)
G = 1
G = 5
+IN
8
PD
7
V
6
S–
–OUT
5
04771-0-001
G = 2
04771-0-002
GENERAL DESCRIPTON
The AD8137 is a low cost differential driver with a rail-to-rail
output that is ideal for driving 12-bit ADCs in systems that are
sensitive to power and cost. The AD8137 is easy to apply, and its
internal common-mode feedback architecture allows its output
common-mode voltage to be controlled by the voltage applied
to one pin. The internal feedback loop also provides inherently
balanced outputs as well as suppression of even-order harmonic
distortion products. Fully differential and single-ended-todifferential gain configurations are easily realized by the
AD8137. External feedback networks consisting of four resistors
determine the amplifier’s closed-loop gain. The power-down
feature is beneficial in critical low power applications.
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 that may result from its use.
Specifications subject to change without notice. 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.
The AD8137 is manufactured on Analog Devices’ proprietary
second generation XFCB process, enabling it to achieve high
levels of performance with very low power consumption.
The AD8137 is available in the small 8-lead SOIC package and
3 mm × 3 mm LFCSP. It is rated to operate over the extended
industrial temperature range of −40°C to +125°C.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved.
AD8137
www.BDTIC.com/ADI
TABLE OF CONTENTS
Specifications..................................................................................... 3
Applications..................................................................................... 18
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution.................................................................................. 6
Pin Configuration and Function Descriptions............................. 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 17
REVISION HISTORY
7/05—Rev. A to Rev. B
Changes to Ordering Guide.......................................................... 24
8/04—Rev. 0 to Rev. A.
A
dded 8-Lead LFCSP.........................................................Universal
Changes to Layout..............................................................Universal
Changes to Product Title................................................................. 1
Changes to Figure 1.......................................................................... 1
Changes to Specifications................................................................ 3
Changes to Absolute Maximum Ratings....................................... 6
Changes to Figure 4 and Figure 5................................................... 7
Added Figure 6, Figure 20, Figure 23, Figure 35, Figure 48,
and Figure 58; Renumbered Successive Figures........................... 7
Changes to Figure 32...................................................................... 12
Changes to Figure 40...................................................................... 13
Changes to Figure 55...................................................................... 16
Changes to Table 7 and Figure 63................................................. 18
Changes to Equation 19................................................................. 19
Changes to Figure 64 and Figure 65............................................. 20
Changes to Figure 66...................................................................... 22
Added Driving an ADC with Greater Than 12-Bit
Performance Section ...................................................................... 22
Changes to Ordering Guide.......................................................... 24
Updated Outline Dimensions....................................................... 24
5/04—Revision 0: Initial Version
Analyzing a Typical Application with Matched R and R
Networks
Estimating Noise, Gain, and Bandwith with Matched
Feedback Networks.................................................................... 18
Driving an ADC with Greater than 12-Bit Performance ...... 22
Outline Dimensions ....................................................................... 24
Ordering Guide .......................................................................... 24
...................................................................................... 18
F G
Rev. B | Page 2 of 24
AD8137
www.BDTIC.com/ADI
SPECIFICATIONS
VS = ±5 V, V
Table 1.
Parameter Conditions Min Typ Max Unit
DIFFERENTIAL INPUT PERFORMANCE
DYNAMIC PERFORMANCE
−3 dB Small Signal Bandwidth V
−3 dB Large Signal Bandwidth V
Slew Rate V
Settling Time to 0.02% V
Overdrive Recovery Time G = 2, V
NOISE/HARMONIC PERFORMANCE
SFDR V
V
Input Voltage Noise f = 50 kHz to 1 MHz 8.25 nV/√Hz
Input Current Noise f = 50 kHz to 1 MHz 1 pA/√Hz
DC PERFORMANCE
Input Offset Voltage VIP = VIN = V
Input Offset Voltage Drift T
Input Bias Current T
Input Offset Current 0.1 0.45 µA
Open-Loop Gain 91 dB
INPUT CHARACTERISTICS
Input Common-Mode Voltage Range −4 +4 V
Input Resistance Differential 800 KΩ
Common-mode 400 KΩ
Input Capacitance Common-mode 1.8 pF
CMRR ∆V
OUTPUT CHARACTERISTICS
Output Voltage Swing Each single-ended output, R
Output Current 20 mA
Output Balance Error f = 1 MHz −64 dB
V
to V
OCM
V
DYNAMIC PERFORMANCE
OCM
−3 dB Bandwidth V
Slew Rate V
Gain 0.992 1.000 1.008 V/V
V
INPUT CHARACTERISTICS
OCM
Input Voltage Range −4 +4 V
Input Resistance 35 kΩ
Input Offset Voltage −28 ±11 +28 mV
Input Voltage Noise f = 100 kHz to 1 MHz 18 nV/√Hz
Input Bias Current 0.3 1.1 µA
CMRR ∆V
POWER SUPPLY
Operating Range +2.7 ±6 V
Quiescent Current 3.2 3.6 mA
Quiescent Current, Disabled Power-down = low 750 900 µA
PSRR ∆VS = ±1 V 79 91 dB
PD
PIN
Threshold Voltage VS− + 0.7 VS− + 1.7 V
Input Current Power-Down = high/low 150/210 170/240 µA
OPERATING TEMPERATURE RANGE −40 +125 °C
= 0 V (@ 25°C, differential gain = 1, R
OCM
= 0.1 V p-p 64 76 MHz
O, dm
= 2 V p-p 79 110 MHz
O, dm
= 2 V step 450 V/µs
O, dm
= 3.5 V step 100 ns
O, dm
= 2 V p-p, fC = 500 kHz 90 dB
O, dm
= 2 V p-p, fC = 2 MHz 76 dB
O, dm
to T
MIN
to T
MIN
= ±1 V 66 79 dB
ICM
PERFORMANCE
O, cm
= 0.1 V p-p 58 MHz
O, cm
= 0.5 V p-p 63 V/µs
O, cm
O, dm
= RF = RG = 1 kΩ, unless otherwise noted, T
L, dm
= 12 V p-p triangle wave 85 ns
I, dm
/∆V
MAX
MAX
OCM
= 0 V
OCM
= 1 kΩ VS− + 0.55 VS+ − 0.55 V
L, dm
, ∆V
= ±0.5 V 62 75 dB
OCM
−2.6 ±0.7 +2.6 mV
3 µV/°C
0.5 1 µA
MIN
to T
= −40°C to +125°C).
MAX
Rev. B | Page 3 of 24
AD8137
www.BDTIC.com/ADI
VS = 5 V, V
Table 2.
Parameter Conditions Min Typ Max Unit
DIFFERENTIAL INPUT PERFORMANCE
DYNAMIC PERFORMANCE
−3 dB Small Signal Bandwidth V
−3 dB Large Signal Bandwidth V
Slew Rate V
Settling Time to 0.02% V
Overdrive Recovery Time G = 2, V
NOISE/HARMONIC PERFORMANCE
SFDR V
V
Input Voltage Noise f = 50 kHz to 1 MHz 8.25 nV/√Hz
Input Current Noise f = 50 kHz to 1 MHz 1 pA/√Hz
DC PERFORMANCE
Input Offset Voltage VIP = VIN = V
Input Offset Voltage Drift T
Input Bias Current T
Input Offset Current 0.1 0.45 µA
Open-Loop Gain 89 dB
INPUT CHARACTERISTICS
Input Common-Mode Voltage Range 1 4 V
Input Resistance Differential 800 KΩ
Common-mode 400 KΩ
Input Capacitance Common-mode 1.8 pF
CMRR ∆V
OUTPUT CHARACTERISTICS
Output Voltage Swing Each single-ended output, R
Output Current 20 mA
Output Balance Error f = 1 MHz −64 dB
V
to V
OCM
V
DYNAMIC PERFORMANCE
OCM
−3 dB Bandwidth V
Slew Rate V
Gain 0.980 1.000 1.020 V/V
V
INPUT CHARACTERISTICS
OCM
Input Voltage Range 1 4 V
Input Resistance 35 kΩ
Input Offset Voltage −25 ±7.5 +25 mV
Input Voltage Noise f = 100 kHz to 5 MHz 18 nV/√Hz
Input Bias Current 0.25 0.9 µA
CMRR ∆V
POWER SUPPLY
Operating Range +2.7 ±6 V
Quiescent Current 2.6 2.8 mA
Quiescent Current, Disabled Power-down = low 450 600 µA
PSRR ∆VS = ±1 V 79 91 dB
PD
PIN
Threshold Voltage VS− + 0.7 VS− + 1.5 V
Input Current Power-down = high/low 50/110 60/120 µA
OPERATING TEMPERATURE RANGE −40 +125 °C
= 2.5 V (@ 25°C, differential gain = 1, R
OCM
= 0.1 V p-p 63 75 MHz
O, dm
= 2 V p-p 76 107 MHz
O, dm
= 2 V step 375 V/µs
O, dm
= 3.5 V step 110 ns
O, dm
= 2 V p-p, fC = 500 kHz 89 dB
O, dm
= 2 V p-p, fC = 2 MHz 73 dB
O, dm
to T
MIN
to T
MIN
= ±1 V 64 90 dB
ICM
PERFORMANCE
O, cm
= 0.1 V p-p 60 MHz
O, cm
= 0.5 V p-p 61 V/µs
O, cm
O, dm
= RF = RG = 1 kΩ, unless otherwise noted, T
L, dm
= 7 V p-p triangle wave 90 ns
I, dm
MAX
MAX
/∆V
OCM
OCM
= 0 V
= 1 kΩ VS− + 0.45 VS+ − 0.45 V
L, dm
, ∆V
= ±0.5 V 62 75 dB
OCM
−2.7 ±0.7 +2.7 mV
3 µV/°C
0.5 0.9 µA
MIN
to T
= −40°C to +125°C).
MAX
Rev. B | Page 4 of 24
AD8137
www.BDTIC.com/ADI
VS = 3 V, V
Table 3.
Parameter Conditions Min Typ Max Unit
DIFFERENTIAL INPUT PERFORMANCE
DYNAMIC PERFORMANCE
−3 dB Small Signal Bandwidth V
−3 dB Large Signal Bandwidth V
Slew Rate V
Settling Time to 0.02% V
Overdrive Recovery Time G = 2, V
NOISE/HARMONIC PERFORMANCE
SFDR V
V
Input Voltage Noise f = 50 kHz to 1 MHz 8.25 nV/√Hz
Input Current Noise f = 50 kHz to 1 MHz 1 pA/√Hz
DC PERFORMANCE
Input Offset Voltage VIP = VIN = V
Input Offset Voltage Drift T
Input Bias Current T
Input Offset Current 0.1 0.4 µA
Open-Loop Gain 87 dB
INPUT CHARACTERISTICS
Input Common-Mode Voltage Range 1 2 V
Input Resistance Differential 800 MΩ
Common-mode 400 MΩ
Input Capacitance Common-mode 1.8 pF
CMRR ∆V
OUTPUT CHARACTERISTICS
Output Voltage Swing Each single-ended output, R
Output Current 20 mA
Output Balance Error f = 1 MHz −64 dB
V
to V
OCM
V
DYNAMIC PERFORMANCE
OCM
−3 dB Bandwidth V
Slew Rate V
Gain 0.96 1.00 1.04 V/V
V
INPUT CHARACTERISTICS
OCM
Input Voltage Range 1.0 2.0 V
Input Resistance 35 kΩ
Input Offset Voltage −25 ±5.5 +25 mV
Input Voltage Noise f = 100 kHz to 5 MHz 18 nV/√Hz
Input Bias Current 0.3 0.7 µA
CMRR ∆V
POWER SUPPLY
Operating Range +2.7 ±6 V
Quiescent Current 2.3 2.5 mA
Quiescent Current, Disabled Power-down = low 345 460 µA
PSRR ∆VS = ±1 V 78 90 dB
PD
PIN
Threshold Voltage VS− + 0.7 VS− + 1.5 V
Input Current Power-down = high/low 8/65 10/70 µA
OPERATING TEMPERATURE RANGE −40 +125 °C
= 1.5 V (@ 25°C, differential gain = 1, R
OCM
O, dm
O, dm
O, dm
O, dm
O, dm
O, dm
to T
MIN
to T
MIN
ICM
PERFORMANCE
O, cm
O, cm
O, cm
O, dm
= RF = RG = 1 kΩ, unless otherwise noted, T
L, dm
MIN
to T
= −40°C to +125°C).
MAX
= 0.1 V p-p 61 73 MHz
= 2 V p-p 62 93 MHz
= 2 V Step 340 V/µs
= 3.5 V Step 110 ns
= 5 V p-p Triangle Wave 100 ns
I, dm
= 2 V p-p, fC = 500 kHz 89 dB
= 2 V p-p, fC = 2 MHz 71 dB
MAX
MAX
OCM
= 0 V
−2.75 ±0.7 +2.75 mV
3 µV/°C
0.5 0.9 µA
= ±1 V 64 80 dB
= 1 kΩ VS− + 0.37 VS+ − 0.37 V
L, dm
= 0.1 V p-p 61 MHz
= 0.5 V p-p 59 V/µs
/∆V
, ∆V
OCM
= ±0.5 V 62 74 dB
OCM
Rev. B | Page 5 of 24
AD8137
www.BDTIC.com/ADI
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter Rating
Supply Voltage 12 V
V
OCM
VS+ to V
S−
Power Dissipation See Figure 3
Input Common-Mode Voltage VS+ to V
S−
Storage Temperature −65°C to +125°C
Operating Temperature Range −40°C to +125°C
Lead Temperature (Soldering 10 sec) 300°C
Junction Temperature 150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and 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.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, θJA is
specified for the device soldered in a circuit board in still air.
Table 5. Thermal Resistance
Package Type θ
JA
SOIC-8/2-Layer 157 56 °C/W
SOIC-8/4-Layer 125 56 °C/W
LFCSP/4-Layer 70 56 °C/W
Maximum Power Dissipation
The maximum safe power dissipation in the AD8137 package is
limited by the associated rise in junction temperature (T
the die. At approximately 150°C, which is the glass transition
temperature, the plastic changes 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 AD8137. Exceeding a junction
temperature of 175°C for an extended period of time can result
in changes in the silicon devices, potentially causing failure.
θ
JC
Unit
) on
J
The power dissipated in the package (P
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 (V
quiescent current (I
and common-mode currents flowing to the load, as well as
currents flowing through the external feedback networks and
the internal common-mode feedback loop. The internal resistor
tap used in the common-mode feedback loop places a 1 kΩ
differential load on the output. RMS output voltages should be
considered when dealing with ac signals.
Airflow reduces θ
the package leads from metal traces, through holes, ground,
and power planes reduces the θ
Figure 3 shows the maximum safe power dissipation in the
package vs. the ambient temperature for the SOIC-8 (125°C/W)
and LFCSP (θ
4-layer board. θ
3.0
2.5
2.0
1.5
1.0
0.5
MAXIMUM POWER DISSIPATION (W)
0
–40 –20–10–30 0 10 20 30 40 50 60 70 80 90 100110120
Figure 3. Maximum Power Dissipation vs. Temperature for a 4-Layer Board
) is the sum of the
D
) times the
S
). The load current consists of differential
S
. Also, more metal directly in contact with
JA
.
JA
= 70°C/W) package on a JEDEC standard
JA
values are approximations.
JA
LFCSP
SOIC-8
AMBIENT TEMPERATURE (°C)
04771-0-022
ESD 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 this product 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 | Page 6 of 24
AD8137
www.BDTIC.com/ADI
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
AD8137
–IN
1
2
V
OCM
V
3
S+
+OUT
4
Figure 4. Pin Configuration
Table 6. Pin Function Descriptions
Pin No. Mnemonic Description
1 −IN Inverting Input.
2 V
3 V
OCM
S+
An internal feedback loop drives the output common-mode voltage to be equal to the voltage applied to
the V
pin, provided the amplifier’s operation remains linear.
OCM
Positive Power Supply Voltage.
4 +OUT Positive Side of the Differential Output.
5 −OUT Negative Side of the Differential Output.
6 V
7
S−
PD
Negative Power Supply Voltage.
Power Down.
8 +IN Noninverting Input.
+IN
8
PD
7
V
6
S–
–OUT
5
04771-0-001
R
F
V
TEST
TEST
SIGNAL
SOURCE
50Ω
50Ω
52.3Ω
MIDSUPPLY
52.3Ω
RG= 1kΩ
RG= 1kΩ
Figure 5. Basic Test Circuit
V
OCM
C
F
+
AD8137
–
C
F
R
F
R
L, dm
1kΩ V
–
+
O, dm
04771-0-023
V
TEST
TEST
SIGNAL
SOURCE
50Ω
50Ω
52.3Ω
MIDSUPPLY
52.3Ω
RG= 1kΩ
V
RG= 1kΩ
Figure 6. Capacitive Load Test Circuit, G = 1
OCM
RF= 1kΩ
+
AD8137
–
R
= 1kΩ
F
R
S
C
L, dm
R
S
–
R
L, dmVO, dm
+
04771-0-062
Rev. B | Page 7 of 24
AD8137
www.BDTIC.com/ADI
TYPICAL PERFORMANCE CHARACTERISTICS
Unless otherwise noted, differential gain = 1, RG = RF = R
Figure 5 for the definition of terms.
3
2
1
0
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
RG= 1kΩ
NORMALIZED CLOSED-LOOP GAIN (dB)
–11
–12
= 0.1V p-p
V
O, dm
0.1 1 10 100 1000
Figure 7. Small Signal Frequency Response for Various Gains
3
2
1
0
–1
–2
–3
–4
–5
–6
–7
–8
CLOSED-LOOP GAIN (dB)
–9
–10
–11
V
= 0.1V p-p
O, dm
–12
1 10 100 1000
Figure 8. Small Signal Frequency Response for Various Power Supplies
3
2
1
0
–1
–2
–3
–4
–5
–6
–7
–8
CLOSED-LOOP GAIN (dB)
–9
–10
–11
V
= 0.1V p-p
O, dm
–12
1 10 100 1000
Figure 9. Small Signal Frequency Response at Various Temperatures
G = 1
G = 5
G = 10
FREQUENCY (MHz)
VS = +5
VS = ±5
FREQUENCY (MHz)
T = +85°C
T = +125°C
FREQUENCY (MHz)
G = 2
VS = +3
T = +25°C
T = –40°C
= 1 kΩ, VS = 5 V, TA = 25°C, V
L, dm
04771-0-002
04771-0-003
04771-0-006
= 2.5V. Refer to the basic test circuit in
OCM
3
2
1
0
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
NORMALIZED CLOSED-LOOP GAIN (dB)
RG= 1kΩ
–11
–12
= 2.0V p-p
V
O, dm
0.1 1 10 100 1000
G = 1
G = 5
G = 10
FREQUENCY (MHz)
G = 2
Figure 10. Large Signal Frequency Response for Various Gains
4
3
2
1
0
–1
–2
–3
–4
–5
–6
–7
CLOSED-LOOP GAIN (dB)
–8
–9
–10
V
= 2.0V p-p
O, dm
–11
1 10 100 1000
VS = +5
VS = ±5
FREQUENCY (MHz)
VS = +3
Figure 11. Large Signal Frequency Response for Various Power Supplies
4
3
2
1
0
–1
–2
–3
–4
–5
–6
–7
CLOSED-LOOP GAIN (dB)
–8
–9
–10
V
= 2.0V p-p
O, dm
–11
1 10 100 1000
T = +25°C
T = +85°C
T = +125°C
T = –40°C
FREQUENCY (MHz)
Figure 12. Large Signal Frequency Response at Various Temperatures
04771-0-004
04771-0-005
04771-0-007
Rev. B | Page 8 of 24
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