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Analog Devices |
Data Sheet
FEATURES
Easy to use, single-ended-to-differential conversion
Adjustable output common-mode voltage
Externally adjustable gain
Low harmonic distortion
−94 dBc SFDR at 5 MHz
−85 dBc SFDR at 20 MHz
−3 dB bandwidth of 320 MHz, G = +1
Fast settling to 0.01% of 16 ns
Slew rate 1150 V/µs
Fast overdrive recovery of 4 ns
Low input voltage noise of 5 nV/√Hz
1 mV typical offset voltage
Wide supply range +3 V to ±5 V
Low power 90 mW on 5 V
0.1 dB gain flatness to 40 MHz
Available in 8-Lead SOIC and MSOP packages
APPLICATIONS
ADC drivers
Single-ended-to-differential converters
IF and baseband gain blocks
Differential buffers
Line drivers
GENERAL DESCRIPTION
The AD8138 is a major advancement over op amps for
differential signal processing. The AD8138 can be used as a
single-ended-to-differential amplifier or as a differential-to-
differential amplifier. The AD8138 is as easy to use as an op
amp and greatly simplifies differential signal amplification and
driving. Manufactured on the proprietary ADI XFCB bipolar
process, the AD8138 has a −3 dB bandwidth of 320 MHz and
delivers a differential signal with the lowest harmonic distortion
available in a differential amplifier. The AD8138 has a unique
internal feedback feature that provides balanced output gain
and phase matching, suppressing even order harmonics. The
internal feedback circuit also minimizes any gain error that
would be associated with the mismatches in the external gain
setting resistors.
The differential output of the AD8138 helps balance the input
to differential ADCs, maximizing the performance of the ADC.
Low Distortion,
Differential ADC Driver
AD8138
PIN CONFIGURATION
–IN 1
VOCM 2
V+ 3
+OUT 4
AD8138
8 +IN
7 NC
6 V–
5 –OUT
NC = NO CONNECT
Figure 1.
TYPICAL APPLICATION CIRCUIT
5V
499Ω
VIN 499Ω +
VOCM
AD8138
499Ω
–
5V
AVDD DVDD
AIN
ADC
AIN
AVSS
VREF
DIGITAL
OUTPUTS
499Ω
Figure 2.
The AD8138 eliminates the need for a transformer with high
performance ADCs, preserving the low frequency and dc infor-
mation. The common-mode level of the differential output is
adjustable by a voltage on the VOCM pin, easily level-shifting the
input signals for driving single-supply ADCs. Fast overload
recovery preserves sampling accuracy.
The AD8138 distortion performance makes it an ideal ADC
driver for communication systems, with distortion performance
good enough to drive state-of-the-art 10-bit to 16-bit converters
at high frequencies. The high bandwidth and IP3 of the
AD8138 also make it appropriate for use as a gain block in IF
and baseband signal chains. The AD8138 offset and dynamic
performance makes it well suited for a wide variety of signal
processing and data acquisition applications.
The AD8138 is available in both SOIC and MSOP packages for
operation over −40°C to +85°C temperatures.
Rev. G
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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.
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One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©1999–2016 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
AD8138* Product Page Quick Links
Last Content Update: 11/01/2016
Comparable Parts
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Evaluation Kits
• Universal Evaluation Board for Single Differential
Amplifiers
Documentation
Application Notes
• AN-0990: Terminating a Differential Amplifier in Single-
Ended Input Applications
• AN-0992: Active Filter Evaluation Board for Differential
Amplifiers
• AN-1026: High Speed Differential ADC Driver Design
Considerations
• AN-1363: Meeting Biasing Requirements of Externally
Biased RF/Microwave Amplifiers with Active Bias
Controllers
• AN-584: Using the AD813X Differential Amplifier
• AN-589: Ways to Optimize the Performance of a
Difference Amplifier
• AN-649: Using the Analog Devices Active Filter Design
Tool
Data Sheet
• AD8138-DSCC: Military Data Sheet
• AD8138-EP: Enhanced Product Data Sheet
• AD8138: Low Distortion Differential ADC Driver Data
Sheet
User Guides
• UG-474: Evaluation Board for Differential Amplifiers
Offered in 8-Lead SOIC Packages
• UG-888: Evaluation Board for Differential Amplifiers
Offered in 8-Lead MSOP Packages
Tools and Simulations
• ADI DiffAmpCalc™
• AD8138 SPICE Macro-Model
Reference Designs
• CN0040
• CN0041
• CN0061
Reference Materials
Product Selection Guide
• High Speed Amplifiers Selection Table
Technical Articles
• Maximize Performance When Driving Differential ADCs
Tutorials
• MT-075: Differential Drivers for High Speed ADCs
Overview
• MT-076: Differential Driver Analysis
• MT-218: Multiple Feedback Band-Pass Design Example
• MT-230: Noise Considerations in High Speed Converter
Signal Chains
Design Resources
• AD8138 Material Declaration
• PCN-PDN Information
• Quality And Reliability
• Symbols and Footprints
Discussions
View all AD8138 EngineerZone Discussions
Sample and Buy
Visit the product page to see pricing options
Technical Support
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