ADA4950-1YCPZ - Differential ADC Driver G=1/2/3 | ADI

The ADA4950-1YCPZ is a low power, selectable gain differential ADC driver from Analog Devices, Inc. It provides fixed gains of 1, 2, or 3 using on-chip feedback and gain resistors, eliminating the need for external resistor networks and reducing BOM area. The device is packaged in a 16-lead LFCSP-VQ (3x3 mm) and supports a single supply range of 3 V to 11 V or a dual supply range of ±1.5 V to ±5.5 V. It is designed for driving high performance analog-to-digital converters (ADCs) in both single-ended-to-differential and differential-to-differential configurations.

A differential ADC driver is a specialized amplifier that converts a single-ended or differential analog signal into a balanced differential output centered at a desired common-mode voltage, which is essential for driving modern high-speed ADCs. These converters rely on differential inputs to improve common-mode noise rejection, reduce even-order harmonic distortion, and double the dynamic range compared with single-ended driver solutions. Within the signal chain hierarchy, the ADC driver sits between the anti-aliasing filter and the converter input, providing scaling, buffering, and level shifting.

Key features of the ADA4950-1 include on-chip gain select pins for G=1, 2, 3, low power consumption enabled by the proprietary silicon-germanium (SiGe) complementary bipolar process, and 114 mA output current per channel. The internal feedback network maintains excellent gain accuracy without external precision resistors, and the low distortion and noise floor suit demanding data acquisition and communications applications.

The SiGe complementary bipolar fabrication process provides the ADA4950-1 with a favorable speed-to-power ratio, making it possible to achieve wide bandwidths and low harmonic distortion while consuming less quiescent current than amplifiers built in older bipolar processes. The ADA4950-1 is the single-channel version; the ADA4950-2 is the dual-channel companion for multichannel systems.

Typical applications include high-speed ADC input stages in instrumentation, IF sampling and baseband signal chains in software-defined radios, differential buffering for sensors, and ultrasound and radar preprocessing. The 3x3 mm LFCSP package supports compact board layouts.

When designing with the ADA4950-1, connect the gain select pins according to the desired closed-loop gain and place 0.1 uF decoupling capacitors as close as possible to the supply pins. The output common-mode voltage must be set within the ADC input range to avoid clipping and preserve converter dynamic performance.