Ultralow Distortion,

Differential ADC Driver

Data Sheet

ADA4939-1/ADA4939-2

Rev. A

Document Feedback

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibilityis assumedbyAnalogDevicesforitsuse,norforanyinfringementsof patentsorother

rightsofthirdpartiesthatmayresultfromitsuse.Specificationssubjecttochangewithoutnotice.No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

©2008–2016 Analog Devices, Inc. All rights reserved.

Technical Support

www.analog.com

FEATURES

Extremely low harmonic distortion

−102 dBc HD2 at 10 MHz

−83 dBc HD2 at 70 MHz

−77 dBc HD2 at 100 MHz

−101 dBc HD3 at 10 MHz

−97 dBc HD3 at 70 MHz

−91 dBc HD3 at 100 MHz

Low input voltage noise: 2.3 nV/√Hz

High speed

−3 dB bandwidth of 1.4 GHz, G = 2

Slew rate: 6800 V/μs, 25% to 75%

Fast overdrive recovery of <1 ns

±0.5 mV typical offset voltage

Externally adjustable gain

Stable for differential gains ≥2

Differential-to-differential or single-ended-to-differential

operation

Adjustable output common-mode voltage

Single-supply operation: 3.3 V to 5 V

APPLICATIONS

ADC drivers

Single-ended-to-differential converters

IF and baseband gain blocks

Differential buffers

Line drivers

GENERAL DESCRIPTION

The ADA4939-1/ADA4939-2 are low noise, ultralow distortion,

high speed differential amplifiers. They are an ideal choice for

driving high performance ADCs with resolutions up to 16 bits

from dc to 100 MHz. The output common-mode voltage is user

adjustable by means of an internal common-mode feedback loop,

allowing the ADA4939-1/ADA4939-2 output to match the input

of the ADC. The internal feedback loop also provides exceptional

output balance as well as suppression of even-order harmonic

distortion products.

With the ADA4939-1/ADA4939-2, differential gain configurations

are easily realized with a simple external feedback network of four

resistors that determine the closed-loop gain of the amplifier.

The ADA4939-1/ADA4939-2 are fabricated using Analog Devices,

Inc., proprietary silicon-germanium (SiGe), complementary bipolar

process, enabling them to achieve very low levels of distortion with

an input voltage noise of only 2.3 nV/√Hz. The low dc offset and

excellent dynamic performance of the ADA4939-1/ADA4939-2

make them well suited for a wide variety of data acquisition and

signal processing applications.

FUNCTIONAL BLOCK DIAGRAMS

–FB

+IN

–IN

+FB

–OUT

PD

+OUT

12

11

10

1

3

49

2

ADA4939-1

Figure 1. ADA4939-1

–IN1

+FB1

–FB2

+IN2

+OUT1

ADA4939-2

PD2

–OUT2

2

1

3

4

5

6

18

17

16

15

14

13

Figure 2. ADA4939-2

The ADA4939-1 (single) is available in a 3 mm × 3 mm, 16-lead

LFCSP, and the ADA4939-2 (dual) is available in a 4 mm × 4 mm,

24-lead LFCSP. The pinouts are optimized to facilitate printed

circuit board (PCB) layout and minimize distortion. The

ADA4939-1/ADA4939-2 are specified to operate over the

−40°C to +105°C temperature range; both operate on supplies

between 3.3 V and 5 V.

–60

–110

–105

–100

–95

–90

–85

–80

–75

–70

–65

1

10

100

FREQUENCY (MHz)

HD2

HD3

Figure 3. Harmonic Distortion vs. Frequency