Ultra-Low Distortion

Differential ADC Driver

Preliminary Technical Data

ADA4938-1

Rev. PrA

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FEATURES

Extremely low harmonic distortion

−108 dBc HD2 @ 10 MHz

−79 dBc HD2 @ 70 MHz

−125 dBc HD3 @ 10 MHz

−87 dBc HD3 @ 70 MHz

Low input voltage noise: 2.2 nV/√Hz

High speed

−3 dB bandwidth of 1.5 GHz, G = 1

Slew rate: 4700 V/μs

0.1 dB gain flatness to 125 MHz

Fast settling to 0.01% in 8.5 ns

Fast overdrive recovery of 4 ns

1 mV typical offset voltage

Externally adjustable gain

Differential to differential or single-ended to differential

operation

Adjustable output common-mode voltage

Wide Supply Voltage Range: +5 V & ± 5 V

Pb-free 3 mm x 3 mm LFCSP package

APPLICATIONS

ADC drivers

Single-ended-to-differential converters

IF and baseband gain blocks

Differential buffers

Line drivers

FUNCTIONAL BLOCK DIAGRAM

Figure 1.

GENERAL DESCRIPTION

The ADA4938-1 is a low noise, ultra-low distortion, high speed

differential amplifier. It is an ideal choice for driving high

performance ADCs with resolutions up to 16 bits from dc to 70

MHz. The output common mode voltage is adjustable over a

wide range, allowing the ADA4938-1 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 ADA4938-1. A

simple external feedback network of four resistors determines

the amplifier’s closed-loop gain.

The ADA4938-1 is fabricated using ADI’s proprietary third

generation high-voltage XFCB process, enabling it to achieve

very low levels of distortion with input voltage noise of only 2.2

nV/√Hz. The low dc offset and excellent dynamic performance

of the ADA4938-1 make it well suited for a wide variety of data

acquisition and signal processing and applications.

The ADA4938-1 is available in a Pb-free, 3 mm x 3mm lead

frame chip scale package (LFCSP). It is specified to operate

over the extended industrial temperature range of −40°C to

+85°C.