New differential amplifier drives 14- and 16-bit ADCs in communications and high-speed instrumentation applications.

Norwood, MA (06/10/2008) - Analog Devices, Inc. (ADI) today extended its family of differential amplifiers by introducing a new device with the industry’s best distortion performance at the lowest power consumption for engineers who need maximum performance when driving high-resolution ADCs (analog-to-digital converters) in communications infrastructure, instrumentation and other high-speed equipment. Optimized to drive today’s high-performance 14- and 16-bit converters, the ADA4939 differential amplifier consumes less than 120 mW of power on a single 3.3-V supply, while achieving 82-dB SFDR (spurious-free dynamic range) at 70 MHz. The new differential amplifier is available in one- and two-channel versions that can drive ADCs with resolutions up to 16 bits, such as ADI’s AD9460 and AD9461ADCs, and can drive low-power, 14-bit ADCs, such as ADI’s AD9246.

The ADA4939 can be used in either differential-to-differential or single-ended-to-differential configurations. An internal common-mode feedback loop allows the user to independently adjust the ADA4939 output common-mode level to match the input common mode voltage of the ADC, and at the same time achieve exceptional output balance and suppression of even-order harmonics.

The ADA4939 is especially well suited to communications applications, such as cellular base stations using low IF (intermediate frequency) and baseband signal processing at frequencies up to 100 MHz, and where 14- and 16 bit accuracy is required. The two-channel version, the ADA4939-2, is ideal for driving dual ADCs used in I/Q demodulation schemes. It offers low cross-talk of –80 dB at 100 MHz while providing gain and phase matching.

The ADA4939 is fabricated using ADI’s proprietary silicon-germanium (SiGe) complementary bipolar process, enabling it to achieve very low levels of distortion with an input voltage noise of 2.3 nV/rt Hz, as well as –3 dB bandwidth of 1.4 GHz (G=+2) and a slew rate of 5000 V/µS. The ADA4939 is specified to operate over the −40 degrees C to +105 degrees C temperature range for both 3.3-V and 5-V operation.

Availability and Pricing
The ADA4939-1 and ADA4939-2 are available now in production quantities. The ADA4939-1 is housed in a Pb-free, 3 mm × 3 mm 16-lead LFCSP (lead-frame chip-scale package), and the two-channel ADA4939-2 comes in a 4 mm × 4 mm 24-lead LFCSP. The ADA4939-1 is priced at $3.79 per unit in 1,000-unit quantities, and the ADA4939-2 is priced at $5.69 per unit in 1,000-unit quantities. For more information, visit ADA4939. For more information on driving ADCs, visit

About Analog Devices

Innovation, performance, and excellence are the cultural pillars on which Analog Devices has built one of the longest standing, highest growth companies within the technology sector. Acknowledged industry-wide as the world leader in data conversion and signal conditioning technology, Analog Devices serves over 100,000 customers, representing virtually all types of electronic equipment. Analog Devices is headquartered in Norwood, Massachusetts, with design and manufacturing facilities throughout the world. Analog Devices is included in the S&P 500 Index.

Editor's Contact Information:

Sue Martenson

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