Description

The ADA4939-1 / ADA4939-2 are low noise, ultralow distortion,high speed differential amplifiers. They are an ideal choice fordriving high performance ADCs with resolutions up to 16 bitsfrom dc to 100 MHz. The output common-mode voltage is useradjustable by means of an internal common-mode feedback loop,allowing the ADA4939-1 / ADA4939-2 output to match the inputof the ADC. The internal feedback loop also provides exceptionaloutput balance as well as suppression of even-order harmonicdistortion products.With the ADA4939-1 / ADA4939-2, differential gain configurationsare easily realized with a simple external feedback network of fourresistors 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 bipolarprocess, enabling them to achieve very low levels of distortion withan input voltage noise of only 2.3 nV/√Hz. The low dc offset andexcellent dynamic performance of the ADA4939-1 / ADA4939-2make them well suited for a wide variety of data acquisition andsignal processing applications.The ADA4939-1 (single) is available in a 3 mm × 3 mm, 16-leadLFCSP, and the ADA4939-2 (dual) is available in a 4 mm × 4 mm,24-lead LFCSP. The pinouts are optimized to facilitate printedcircuit board (PCB) layout and minimize distortion. TheADA4939-1/ADA4939-2 are specified to operate over the−40°C to +105°C temperature range; both operate on suppliesbetween 3.3 V and 5 V.Applications ADC drivers Single-ended-to-differential converters IF and baseband gain blocks Differential buffers Line drivers