Low Distortion

Differential ADC Driver

AD8138-EP
FEATURES PIN CONFIGURATION
Adjustable output common-mode voltage AD8138-EP
Low harmonic distortion –IN 1 8 +IN
−94 dBc SFDR @ 5 MHz VOCM 2 7 NC

−85 dBc SFDR @ 20 MHz V+ 3 6 V–

+OUT 4 5 –OUT
−3 dB bandwidth of 320 MHz, G = +1

08997-001
Fast settling to 0.01% of 16 ns NC = NO CONNECT

Fast overdrive recovery of 4 ns Figure 1.

Low input voltage noise of 5 nV/√Hz
Low power 90 mW on 5 V
TYPICAL APPLICATION CIRCUIT
ENHANCED PRODUCT FEATURES 5V
5V
499Ω
Supports defense and aerospace applications (AQEC)
Extended temperature range −55ºC to +105°C
499Ω
VIN AVDD DVDD
Controlled manufacturing baseline VOCM
+ AIN
DIGITAL
One assembly/test site AD8138-EP ADC OUTPUTS
499Ω
– AIN VREF
AVSS
One fabrication site
Enhanced product change notification

08997-002
499Ω
Qualification data available on request
Figure 2.

APPLICATIONS
ADC drivers
Single-ended-to-differential converters The AD8138-EP’s differential output helps balance the input to
IF and baseband gain blocks the differential ADCs, maximizing the performance of the ADC.
Differential buffers
The AD8138-EP eliminates the need for a transformer with
Line drivers
high performance ADCs, preserving the low frequency and dc
information. The common-mode level of the differential output
GENERAL DESCRIPTION is adjustable by a voltage on the VOCM pin, easily level-shifting
The AD8138-EP is a major advancement over op amps for the input signals for driving single-supply ADCs. Fast overload
differential signal processing. The AD8138-EP can be used recovery preserves sampling accuracy.
as a single-ended-to-differential amplifier or as a differential-to-
The AD8138-EP distortion performance makes it an ideal ADC
differential amplifier. The AD8138-EP is as easy to use as an op
driver for communication systems, with distortion performance
amp and greatly simplifies differential signal amplification and
good enough to drive state-of-the-art 10-bit to 16-bit converters
driving. Manufactured on Analog Devices, Inc., proprietary XFCB
at high frequencies. The AD8138-EP’s high bandwidth and IP3 also
bipolar process, the AD8138-EP has a −3 dB bandwidth of 320 MHz
make it appropriate for use as a gain block in IF and baseband
and delivers a differential signal with the lowest harmonic distortion
signal chains. The AD8138-EP offset and dynamic performance
available in a differential amplifier. The AD8138-EP has a unique
make it well suited for a wide variety of signal processing and
internal feedback feature that provides balanced output gain and
data acquisition applications. The AD8138-EP is available in the
phase matching, suppressing even order harmonics. The internal
MSOP package for operation over −55°C to +105°C temperatures.
feedback circuit also minimizes any gain error that would be
associated with the mismatches in the external gain setting resistors. Full details about this enhanced product are available in the
AD8138 data sheet, which should be consulted in conjunction
with this data sheet.

Rev. 0
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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Tel: 781.329.4700 www.analog.com
Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 ©2010 Analog Devices, Inc. All rights reserved.
AD8138-EP

TABLE OF CONTENTS
Features .............................................................................................. 1 VOCM to ±OUT Specifications ......................................................6

Enhanced Product Features ............................................................ 1 Absolute Maximum Ratings ............................................................7

Applications ....................................................................................... 1 Thermal Resistance .......................................................................7

General Description ......................................................................... 1 Maximum Power Dissipation ......................................................7

Pin Configuration ............................................................................. 1 ESD Caution...................................................................................7

Typical Application Circuit ............................................................. 1 Maximum Output Voltage Swing................................................8

Revision History ............................................................................... 2 Pin Configuration and Function Descriptions..............................9

Specifications..................................................................................... 3 Outline Dimensions ....................................................................... 10

±DIN to ±OUT Specifications...................................................... 3 Ordering Guide .......................................................................... 10

VOCM to ±OUT Specifications ..................................................... 4

±DIN to ±OUT Specifications...................................................... 5

REVISION HISTORY
4/10—Revision 0: Initial Version

Rev. 0 | Page 2 of 12
 AD8138-EP

SPECIFICATIONS
±DIN TO ±OUT SPECIFICATIONS
At 25°C, VS = ±5 V, VOCM = 0 V, G = +1, RL, dm = 500 Ω, unless otherwise noted. All specifications refer to single-ended input and
differential outputs, unless otherwise noted.
Table 1.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
−3 dB Small Signal Bandwidth VOUT = 0.5 V p-p, CF = 0 pF 290 320 MHz
TMIN to TMAX 1 256 MHz
VOUT = 0.5 V p-p, CF = 1 pF 225 MHz
Bandwidth for 0.1 dB Flatness VOUT = 0.5 V p-p, CF = 0 pF 30 MHz
Large Signal Bandwidth VOUT = 2 V p-p, CF = 0 pF 265 MHz
Slew Rate VOUT = 2 V p-p, CF = 0 pF 1150 V/μs
Settling Time 0.01%, VOUT = 2 V p-p, CF = 1 pF 16 ns
Overdrive Recovery Time VIN = 5 V to 0 V step, G = +2 4 ns
NOISE/HARMONIC PERFORMANCE
Second Harmonic VOUT = 2 V p-p, 5 MHz, RL, dm = 800 Ω −94 dBc
VOUT = 2 V p-p, 20 MHz, RL, dm = 800 Ω −87 dBc
VOUT = 2 V p-p, 70 MHz, RL, dm = 800 Ω −62 dBc
Third Harmonic VOUT = 2 V p-p, 5 MHz, RL, dm = 800 Ω −114 dBc
VOUT = 2 V p-p, 20 MHz, RL, dm = 800 Ω −85 dBc
VOUT = 2 V p-p, 70 MHz, RL, dm = 800 Ω −57 dBc
IMD 20 MHz −77 dBc
IP3 20 MHz 37 dBm
Voltage Noise (RTI) f = 100 kHz to 40 MHz 5 nV/√Hz
Input Current Noise f = 100 kHz to 40 MHz 2 pA/√Hz
INPUT CHARACTERISTICS
Offset Voltage VOS, dm = VOUT, dm/2; VDIN+ = VDIN− = VOCM = 0 V −2.5 ±1 +2.5 mV
TMIN to TMAX1 −4.8 +4.8 mV
Input Bias Current 3.5 7 μA
TMIN to TMAX variation −0.01 μA/°C
Input Resistance Differential 6 MΩ
Common mode 3 MΩ
Input Capacitance 1 pF
Input Common-Mode Voltage −4.7 to +3.4 V
CMRR ΔVOUT, dm/ΔVIN, cm; ΔVIN, cm = ±1 V, −77 −70 dB
TMIN to TMAX1 −69 dB
OUTPUT CHARACTERISTICS
Output Voltage Swing 2 Maximum ΔVOUT; single-ended output 7.75 V p-p
Output Balance Error ΔVOUT, cm/ΔVOUT, dm; ΔVOUT, dm = 1 V −66 dB
1
Specified to ±6 sigma over the −55°C to +105°C operating temperature range.
2
Output swing capabilities vary over operating temperature. See Figure 4 for more information.

Rev. 0 | Page 3 of 12
AD8138-EP
VOCM TO ±OUT SPECIFICATIONS
At 25°C, VS = ±5 V, VOCM = 0 V, G = +1, RL, dm = 500 Ω, unless otherwise noted. All specifications refer to single-ended input and
differential outputs, unless otherwise noted.
Table 2.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
−3 dB Bandwidth 250 MHz
Slew Rate 330 V/μs
INPUT VOLTAGE NOISE (RTI) f = 0.1 MHz to 100 MHz 17 nV/√Hz
DC PERFORMANCE
Input Voltage Range ±3.8 V
Input Resistance 200 kΩ
Input Offset Voltage VOS, cm = VOUT, cm; VDIN+ = VDIN– = VOCM = 0 V −3.5 ±1 +3.5 mV
TMIN to TMAX 1 −10.2 +10.2 mV
Input Bias Current 0.5 μA
VOCM CMRR ΔVOUT, dm/ΔVOCM; ΔVOCM = ±1 V −75 dB
Gain ΔVOUT, cm/ΔVOCM; ΔVOCM = ±1 V, TMIN to TMAX1 0.9955 1 1.0045 V/V
POWER SUPPLY
Operating Range ±1.4 ±5.5 V
Quiescent Current 18 20 23 mA
TMIN to TMAX1 13.2 mA
Power Supply Rejection Ratio ΔVOUT, dm/ΔVS; ΔVS = ±1 V, TMIN to TMAX1 −90 −70 dB
OPERATING TEMPERATURE RANGE −55 +105 °C
1
Specified to ±6 sigma over the −55°C to +105°C operating temperature range.

Rev. 0 | Page 4 of 12
 AD8138-EP
±DIN TO ±OUT SPECIFICATIONS
At 25°C, VS = 5 V, VOCM = 2.5 V, G = +1, RL, dm = 500 Ω, unless otherwise noted. All specifications refer to single-ended input and
differential output, unless otherwise noted.
Table 3.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
−3 dB Small Signal Bandwidth VOUT = 0.5 V p-p, CF = 0 pF 280 310 MHz
TMIN to TMAX 1 242 MHz
VOUT = 0.5 V p-p, CF = 1 pF 225 MHz
Bandwidth for 0.1 dB Flatness VOUT = 0.5 V p-p, CF = 0 pF 29 MHz
Large Signal Bandwidth VOUT = 2 V p-p, CF = 0 pF 265 MHz
Slew Rate VOUT = 2 V p-p, CF = 0 pF 950 V/μs
Settling Time 0.01%, VOUT = 2 V p-p, CF = 1 pF 16 ns
Overdrive Recovery Time VIN = 2.5 V to 0 V step, G = +2 4 ns
NOISE/HARMONIC PERFORMANCE
Second Harmonic VOUT = 2 V p-p, 5 MHz, RL, dm = 800 Ω −90 dBc
VOUT = 2 V p-p, 20 MHz, RL, dm = 800 Ω −79 dBc
VOUT = 2 V p-p, 70 MHz, RL, dm = 800 Ω −60 dBc
Third Harmonic VOUT = 2 V p-p, 5 MHz, RL, dm = 800 Ω −100 dBc
VOUT = 2 V p-p, 20 MHz, RL, dm = 800 Ω −82 dBc
VOUT = 2 V p-p, 70 MHz, RL, dm = 800 Ω −53 dBc
IMD 20 MHz −74 dBc
IP3 20 MHz 35 dBm
Voltage Noise (RTI) f = 100 kHz to 40 MHz 5 nV/√Hz
Input Current Noise f = 100 kHz to 40 MHz 2 pA/√Hz
INPUT CHARACTERISTICS
Offset Voltage VOS, dm = VOUT, dm/2; VDIN+ = VDIN– = VOCM = 0 V −2.5 ±1 +2.5 mV
TMIN to TMAX1 −5.1 +5.1 mV
Input Bias Current 3.5 7 μA
TMIN to TMAX variation −0.01 μA/°C
Input Resistance Differential 6 MΩ
Common mode 3 MΩ
Input Capacitance 1 pF
Input Common-Mode Voltage −0.3 to +3.2 V
CMRR ΔVOUT, dm/ΔVIN, cm; ΔVIN, cm = 1 V −77 −70 dB
TMIN to TMAX1 −69.5 dB
OUTPUT CHARACTERISTICS
Output Voltage Swing 2 Maximum ∆VOUT; single-ended output 2.9 V p-p
Output Balance Error ΔVOUT, cm/ΔVOUT, dm; ΔVOUT, dm = 1 V −65 dB
1
Specified to ±6 sigma over the −55°C to +105°C operating temperature range.
2
Output swing capabilities vary over operating temperature. See Figure 5 for more information.

Rev. 0 | Page 5 of 12
AD8138-EP
VOCM TO ±OUT SPECIFICATIONS
At 25°C, VS = 5 V, VOCM = 2.5 V, G = +1, RL, dm = 500 Ω, unless otherwise noted. All specifications refer to single-ended input and
differential output, unless otherwise noted.
Table 4.
Parameter Conditions Min Typ Max Unit
DYNAMIC PERFORMANCE
−3 dB Bandwidth 220 MHz
Slew Rate 250 V/μs
INPUT VOLTAGE NOISE (RTI) f = 0.1 MHz to 100 MHz 17 nV/√Hz
DC PERFORMANCE
Input Voltage Range 1.0 to 3.8 V
Input Resistance 100 kΩ
Input Offset Voltage VOS, cm = VOUT, cm; VDIN+ = VDIN– = VOCM = 0 V −5 ±1 +5 mV
TMIN to TMAX 1 −9.7 +9.7 mV
Input Bias Current 0.5 μA
VOCM CMRR ΔVOUT, dm/ΔVOCM; ΔVOCM = 2.5 V ± 1 V −70 dB
Gain ΔVOUT, cm/ΔVOCM; ΔVOCM = 2.5 V ± 1 V, TMIN to TMAX1 0.9968 1 1.0032 V/V
POWER SUPPLY
Operating Range 2.7 11 V
Quiescent Current 15 20 21 mA
TMIN to TMAX1 10.6 mA
Power Supply Rejection Ratio ΔVOUT, dm/ΔVS; ΔVS = ± 1 V −90 −70 dB
TMIN to TMAX1 −57 dB
OPERATING TEMPERATURE RANGE −55 +105 °C
1
Specified to ±6 sigma over the −55°C to +105°C operating temperature range.

Rev. 0 | Page 6 of 12
 AD8138-EP

ABSOLUTE MAXIMUM RATINGS

Table 5. The power dissipated in the package (PD) is the sum of the
Parameter Rating quiescent power dissipation and the power dissipated in the
Supply Voltage ±5.5 V package due to the load drive for all outputs. The quiescent
VOCM ±VS power is the voltage between the supply pins (VS) times the
Output Voltage Swing See Figure 4 and Figure 5 quiescent current (IS). The load current consists of the differential
Internal Power Dissipation 550 mW and common-mode currents flowing to the load, as well as
Operating Temperature Range −55°C to +105°C currents flowing through the external feedback networks and
Storage Temperature Range −65°C to +150°C internal common-mode feedback loop. The internal resistor tap
Lead Temperature (Soldering, 10 sec) 300°C used in the common-mode feedback loop places a negligible
Junction Temperature 150°C differential load on the output. RMS voltages and currents should
Stresses above those listed under Absolute Maximum Ratings be considered when dealing with ac signals.
may cause permanent damage to the device. This is a stress
Airflow reduces θJA. In addition, more metal directly in contact
rating only; functional operation of the device at these or any
with the package leads from metal traces, through holes, ground,
other conditions above those indicated in the operational
and power planes reduces the θJA.
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect Figure 3 shows the maximum safe power dissipation vs. the
device reliability. ambient temperature for the 8-lead MSOP (θJA = 145°C/W)
package on a JEDEC standard 4-layer board. θJA values are
THERMAL RESISTANCE
approximations.
θJA is specified for the worst-case conditions, that is, θJA is
1.75
specified for the device soldered in a circuit board in still air.
Table 6. 1.50
MAXIMUM POWER DISSIPATION (W)

Package Type θJA Unit

1.25
8-Lead MSOP/4-Layer 145 °C/W
1.00

MAXIMUM POWER DISSIPATION 0.75

The maximum safe power dissipation in the AD8138-EP package
is limited by the associated rise in junction temperature (TJ) on 0.50

the die. At approximately 150°C, which is the glass transition

0.25
temperature, the plastic changes its properties. Even temporarily
exceeding this temperature limit can change the stresses that the 0

08997-003
65
75
25

45
15

35

85
95
–55
–45
–35
–25
–15

105
–5
5

55

package exerts on the die, permanently shifting the parametric

performance of the AD8138-EP. Exceeding a junction temperature AMBIENT TEMPERATURE (°C)

of 150°C for an extended period can result in changes in the Figure 3. Maximum Power Dissipation vs. Ambient Temperature
silicon devices, potentially causing failure.

ESD CAUTION

Rev. 0 | Page 7 of 12
AD8138-EP
MAXIMUM OUTPUT VOLTAGE SWING Figure 5 shows the maximum output swing over operating
The maximum output voltage swing must be considered in order temperatures for various loads at VS = 5 V operation.
for the AD8138-EP to remain current density compliant over 3

DIFFERENTIAL OUTPUT VOLTAGE SWING (V p-p)

the extended temperature range. The maximum output swing
RL = 300Ω
is dependent on the load resistance and operating temperatures.
Figure 4 shows the maximum output swing over operating 2.6
temperatures for various loads at ±5 V operation.
RL = 200Ω
8
DIFFERENTIAL OUTPUT VOLTAGE SWING (V p-p)

2.2
RL = 6.8kΩ

7 RL = 150Ω

RL = 2kΩ 1.8
6
VS = 5V
VOUT MAX = 2.9V p-p RL = 100Ω
RL = 1kΩ
1.4

08997-005
5
25 35 45 55 65 75 85 95 105 115
AMBIENT TEMPERATURE (°C)

4 Figure 5. Differential Output Voltage Swing vs. Ambient Temperature, VS = 5 V

RL = 500Ω
VS = ±5V
VOUT MAX = 7.75V p-p The following equation can be used to determine the maximum
3 output voltage swing for VS = 5 V:
08997-004

25 35 45 55 65 75 85 95 105 115
AMBIENT TEMPERATURE (°C) Output = (24.36 × ln(RL) − 82.34) × e ( −0.028 × TA )
Figure 4. Differential Output Voltage Swing vs. Ambient Temperature, VS = ±5 V
where:
The following equation can be used to determine the maximum Output is the maximum output voltage swing that cannot exceed
output voltage swing for VS = ±5 V: 2.9 V p-p.
Output = (38.21 × ln(RL) − 169.26) × e ( −0.0293 × TA ) RL is the load resistance (Ω).
TA is the ambient temperature (°C).
where:
Output is the maximum output voltage swing that cannot exceed
7.75 V p-p.
RL is the load resistance (Ω).
TA is the ambient temperature (°C).

Rev. 0 | Page 8 of 12
 AD8138-EP

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

AD8138-EP
–IN 1 8 +IN
VOCM 2 7 NC
V+ 3 6 V–
+OUT 4 5 –OUT

08997-001
NC = NO CONNECT

Figure 6. Pin Configuration

Table 7. Pin Function Descriptions

Pin No. Mnemonic Description
1 −IN Negative Input Summing Node.
2 VOCM Voltage applied to this pin sets the common-mode output voltage with a ratio of 1:1. For example, 1 V dc on
VOCM sets the dc bias level on +OUT and −OUT to 1 V.
3 V+ Positive Supply Voltage.
4 +OUT Positive Output. Note that the voltage at −DIN is inverted at +OUT.
5 −OUT Negative Output. Note that the voltage at +DIN is inverted at –OUT.
6 V− Negative Supply Voltage.
7 NC No Connect.
8 +IN Positive Input Summing Node.

Rev. 0 | Page 9 of 12
AD8138-EP

OUTLINE DIMENSIONS
3.20
3.00
2.80

8 5 5.15
3.20 4.90
3.00 4.65
2.80 1
4

PIN 1
IDENTIFIER

0.65 BSC

0.95 15° MAX

0.85 1.10 MAX
0.75
0.80
0.15 6° 0.23
0.40 0.55
0.05 0° 0.09 0.40
COPLANARITY 0.25
0.10

100709-B
COMPLIANT TO JEDEC STANDARDS MO-187-AA

Figure 7. 8-Lead Mini Small Outline Package [MSOP]

(RM-8)
Dimensions shown in millimeters

ORDERING GUIDE
Model 1 Temperature Range Package Description Package Option Branding
AD8138SRMZ-EP-R7 −55°C to +105°C 8-Lead MSOP, 7" Tape and Reel RM-8 H27
1
Z = RoHS Compliant Part.

Rev. 0 | Page 10 of 12
 AD8138-EP

NOTES

Rev. 0 | Page 11 of 12
AD8138-EP

NOTES

©2010 Analog Devices, Inc. All rights reserved. Trademarks and

registered trademarks are the property of their respective owners.
D08997-0-4/10(0)

Rev. 0 | Page 12 of 12