Analog Devices Inc. ADA4940-1ARZ-R7

Overview

ADA4940-1ARZ-R7 from Analog Devices is an ultralow-power, fully differential ADC driver amplifier optimized for driving high-resolution SAR ADCs up to 16 bits. It delivers 260 MHz small-signal bandwidth, −122 dB THD at 50 kHz, and 3.9 nV/√Hz input voltage noise while consuming only 1.25 mA quiescent current at 5 V supply - enabling precision signal conditioning in portable medical imaging and industrial process control systems.

For engineers reviewing the ADA4940-1ARZ-R7 datasheet, ADA4940-1ARZ-R7 pinout, ADA4940-1ARZ-R7 application, or ADA4940-1ARZ-R7 equivalent, this page provides verified technical context, package-specific pin functions, real-world application mappings, and validated alternative options for low-distortion, rail-to-rail differential signal conditioning with adjustable common-mode output voltage.

Technical Context

The ADA4940-1ARZ-R7 implements a SiGe complementary bipolar architecture with internal common-mode feedback to achieve exceptional output balance (−65 dB error at 1 MHz) and suppression of even-order harmonics. Its dual-loop structure separates differential gain control (via external RF/RG resistors) from VOCM-level setting, enabling independent optimization of signal fidelity and ADC interface compatibility.

It supports flexible single-supply (3–7 V) or split-supply operation, features a dedicated DISABLE pin for power gating (turn-on time < 0.6 µs), and maintains rail-to-rail output swing (−VS + 0.1 V to +VS − 0.1 V) across −40°C to +125°C. The LFCSP package's exposed pad must be connected to −VS or ground for thermal and electrical stability.

Key Specifications

Pinout & Package

The ADA4940-1ARZ-R7 is packaged in a 3 mm × 3 mm, 16-lead LFCSP (Lead Frame Chip Scale Package) with exposed pad. This thermally enhanced package achieves θJA = 91.3°C/W on a 4-layer board and requires the exposed pad to be soldered to −VS or ground for optimal performance and reliability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fully differential amplifier applications.

Compared with ADA4940-1ARZ-R7, ADA4941-1ARZ-R7 trades bandwidth and power for superior dc precision, while AD8137ARMZ-R7 offers simpler biasing but lacks VOCM control and delivers significantly higher harmonic distortion - making ADA4940-1ARZ-R7 the optimal choice for high-fidelity, power-constrained ADC driving.

Availability

ADA4940-1ARZ-R7 is available at Aetrix Electronics and suitable for portable medical imaging, industrial process controls, and high-resolution data acquisition systems requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for ADA4940-1ARZ-R7 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design and manufacturing expertise spanning precision amplifiers, data converters, and RF solutions.

The ADA4940 family was designed specifically to address the signal integrity and power-efficiency challenges of driving modern low-power, high-resolution SAR and Σ-Δ ADCs in space- and energy-constrained applications.

FAQ

What is the recommended power supply configuration for ADA4940-1ARZ-R7 in single-supply applications?

The ADA4940-1ARZ-R7 supports single-supply operation from 3 V to 7 V. For optimal performance, use a clean, well-bypassed 5 V supply with 0.1 µF ceramic capacitors placed within 2 mm of each +VS and −VS pin pair. The VOCM pin should be biased to mid-supply (2.5 V) when interfacing with ADCs requiring symmetric input ranges. Avoid exceeding 7 V to prevent damage per absolute maximum ratings.

How does the DISABLE pin function on ADA4940-1ARZ-R7, and what is its impact on system power?

The DISABLE pin on ADA4940-1ARZ-R7 enables hardware-controlled power gating: logic-low (≤ −VS + 1 V) disables the amplifier, reducing quiescent current to 28.5 µA typical, while logic-high (≥ −VS + 1.8 V) enables normal operation at 1.25 mA. Turn-on time is under 0.6 µs, supporting rapid wake-up in burst-mode data acquisition. This feature directly lowers average system power in duty-cycled applications.

Can ADA4940-1ARZ-R7 drive ADCs with different input common-mode voltage requirements?

Yes - the ADA4940-1ARZ-R7's dedicated VOCM pin allows precise setting of the differential output's common-mode level from −VS + 0.8 V to +VS − 0.7 V. This enables direct interface with ADCs requiring 0.9 V, 1.25 V, 2.0 V, or other non-midsupply common-mode voltages without external resistive dividers, preserving gain accuracy and noise performance.

What is the significance of the exposed pad connection on the ADA4940-1ARZ-R7 LFCSP package?

The exposed pad on the ADA4940-1ARZ-R7 must be soldered to −VS or ground to ensure thermal stability (reducing θJA to 91.3°C/W) and electrical integrity. Leaving it floating degrades PSRR, increases distortion, and risks thermal runaway under sustained load. Proper pad connection also improves high-frequency return path integrity for both supply and output currents.

How does ADA4940-1ARZ-R7 achieve low harmonic distortion despite its ultralow power consumption?

The ADA4940-1ARZ-R7 achieves −122 dB THD at 50 kHz through Analog Devices' SiGe complementary bipolar process, which delivers high fT and low 1/f noise, combined with an internal common-mode feedback loop that actively corrects output balance errors. This architecture suppresses even-order harmonics without increasing quiescent current - unlike CMOS-based drivers that trade power for linearity.