The ADA4938 is a low noise, ultralow distortion, high speed differential amplifier. It is an ideal choice for driving high performance ADCs with resolutions up to 16 bits from dc to 27 MHz, or up to 12 bits from dc to 74 MHz. The output common-mode voltage is adjustable over a wide range, allowing the ADA4938 to match the input of the ADC. The internal common-mode feedback loop also provides exceptional output balance as well as suppression of even-order harmonic distortion products.
Full differential and single-ended-to-differential gain configurations are easily realized with the ADA4938. A simple external feedback network of four resistors determines the closed-loop gain of the amplifier.
The ADA4938 is fabricated using the Analog Devices, Inc. proprietary third-generation, high voltage XFCB process, enabling it to achieve very low levels of distortion with an input voltage noise of only 2.6 nV/√Hz. The low dc offset and excellent dynamic performance of the ADA4938 make it well suited for a wide variety of data acquisition and signal processing applications.
The ADA4938-1 (single amplifier) is available in a Pb-free, 3 mm × 3 mm, 16-lead LFCSP. The ADA4938-2 (dual amplifier) is available in a Pb-free, 4 mm × 4 mm, 24-lead LFCSP. The pinouts have been optimized to facilitate layout and minimize distortion. The parts are specified to operate over the extended industrial temperature range of −40°C to +85°C.
Data Sheet, Rev. 0, 11/07
|Title||Content Type||File Type|
|ADA4938-1/ADA4938-2: Ultralow Distortion Differential ADC Driver Data Sheet (Rev A, 10/2009) (pdf, 655 kB)||Data Sheets|
|AN-1026: High Speed Differential ADC Driver Design Considerations (pdf, 355 kB)||Application Notes|
|AN-0990: Terminating a Differential Amplifier in Single-Ended Input Applications (pdf, 181 kB)||Application Notes|
|AN-0992: Active Filter Evaluation Board for Differential Amplifiers (pdf, 85 kB)||Application Notes|
|AN-282: Fundamentals of Sampled Data Systems (pdf, 2131 kB)||Application Notes|
|AN-649: Using the Analog Devices Active Filter Design Tool (pdf, 5301 kB)||Application Notes|
AN-584: Using the AD813X Differential Amplifier
(pdf, 174 kB)
The AD813x differs from conventional op amps by the external presence of an additional input and output. The additional input, VOGM, controls the output common mode voltage.
AN-589: Ways to Optimize the Performance of a Difference Amplifier
(pdf, 115 kB)
This Application Note presents several ways to build and optimize the performance of a discrete difference amplifier. It also recommends amplifiers that will make the overall solution cost/performance competitive with monolithic instrument amplifiers.
|MT-218: Multiple Feedback Band-Pass Design Example (pdf, 0)||Tutorials|
|MT-076: Differential Driver Analysis (pdf, 95 kB)||Tutorials|
|MT-075: Differential Drivers for High Speed ADCs Overview (pdf, 183 kB)||Tutorials|
A Stress-Free Method for Choosing High-Speed Op Amps
A decision-tree approach to making the critical decision about high-speed op amp selection, including a look at some helpful tools.
UG-132: Evaluation Board User Guide for the ADA492x-1 and ADA493x-1 Family of Differential Amplifiers
(pdf, 226 kB)
Differential Amplifier Evaluation Board for Single 16-lead 3 mm × 3 mm LFCSP Packages
Ask The Application Engineer 36, Wideband A/D Converter Front-End Design Considerations II: Amplifier-or Transformer Drive for the ADC?
(Analog Dialogue, Volume 41 February 2007)
"Rules of the Road" for High-Speed Differential ADC Drivers
(Analog Dialogue, Vol. 43, No. 5, 2009)
|High Speed Amplifiers Selection Table (pdf, 77 kB)||Product Selection Guide|
RF Source Booklet
(PDF, 4353 kB)
RF IC Product Overview - Version P (02/2014)
|RAQs index||Rarely Asked Questions||HTML|
|Glossary of EE Terms||Glossary||HTML|
|Title||Content Type||File Type|
ADI's new ADI DiffAmpCalc is a free, downloadable calculator for designing differential amplifier circuits. The tool is easy to use and features an interactive user interface to quickly get you up and running.
|ADIsim Design/Simulation Tools||HTML|
|ADA4938 SPICE Macro Model||SPICE Models||HTML|
The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.