Ultralow Power, Low Distortion ADC Driver

The ADA4940-1 / ADA4940-2 are low noise, low distortion differential amplifiers with very low power consumption. They are an ideal choice for driving low power, high resolution, high performance SAR and sigma-delta (Σ-Δ) analog-to-digital converters (ADCs) with resolutions up to 18 bits from dc to 1 MHz on only 1.25 mA of quiescent current. The adjustable level of the output common-mode voltage allows the ADA4940-1/ ADA4940-2 to match the input common-mode voltage of multiple ADCs. The internal common-mode feedback loop provides exceptional output balance, as well as suppression of even-order harmonic distortion products.

With the ADA4940-1 / ADA4940-2, differential gain configurations are easily realized with a simple external feedback network of four resistors determining the closed-loop gain of the amplifier. The ADA4940-1 / ADA4940-2 are fabricated using Analog Devices, Inc., complementary bipolar process, enabling them to achieve very low levels of distortion with an input voltage noise of only 3.9 nV/√Hz. The low dc offset and excellent dynamic performance of the ADA4940-1 / ADA4940-2 make them well suited for a variety of data acquisition and signal processing applications.

The ADA4940-1 is available in a Pb-free, 3 mm × 3 mm, 16-lead LFCSP. The ADA4940-2 is available in a Pb-free, 4 mm × 4 mm, 24-lead LFCSP. The pinout is optimized to facilitate printed circuit board (PCB) layout and minimize distortion. The ADA4940-1 / ADA4940-2 are specified to operate over the −40°C to +125°C temperature range.

Applications

* Low power ADC drivers

* Single-ended-to-differential converters

* Differential buffers

* Line drivers

* Medical Imaging

* Industrial Process Control

* Portable Electronics

* Small signal bandwidth: 260 MHz

* Ultralow power 1.25mA

* Extremely low harmonic distortion

* −122 dB THD at 50 kHz

* −96 dB THD at 1 MHz

* Low input voltage noise: 3.9 nV/√Hz

* 0.35 mV maximum offset voltage

* Balanced outputs

* Settling time to 0.1%: 34 ns

* Rail-to-rail output: −VS + 0.1 V to +VS − 0.1 V

* Adjustable output common-mode voltage

* Flexible power supplies: 3 V to 7 V (LFCSP)

* Disable pin to reduce power consumption

* Available in LFCSP and SOIC packages