Analog Devices Inc. AD604ARZ-RL

Overview

AD604ARZ-RL from Analog Devices is a dual-channel, ultralow-noise, linear-in-dB variable gain amplifier (VGA) with 0.80 nV/√Hz input voltage noise, 40 MHz −3 dB bandwidth, and ±1.0 dB absolute gain accuracy across 0 dB to 48 dB per channel. It integrates a 300 kΩ-input preamplifier and differential ladder attenuator (DSX), enabling precise time-gain control in ultrasound front-ends.

For engineers reviewing the AD604ARZ-RL datasheet, AD604ARZ-RL pinout, AD604ARZ-RL application, or AD604ARZ-RL equivalent, this page delivers verified specifications, validated pin functions, confirmed dual-channel crosstalk performance (−30 dB at 1 MHz), and real-world design context for medical imaging and high-dynamic-range AGC systems.

Technical Context

The AD604ARZ-RL implements a two-stage architecture per channel: a low-noise preamplifier (14 dB or 20 dB selectable gain, 0.73–0.80 nV/√Hz input noise) followed by a differential R-1.5R ladder attenuator (0 dB to 48.36 dB range) and fixed-gain active feedback amplifier (34.4 dB). Gain scaling is programmable from 20 dB/V to 40 dB/V via VREF.

Each channel features unipolar gain control (VGN = 0.1 V to 2.9 V), power-down capability (<50 mV disables channel to 1.9 mA), and independent VOCM setting for output common-mode level. Input-referred noise remains stable across temperature (±2 nV/√Hz variation from −40°C to +85°C), and group delay variation is ±2 ns over 1–10 MHz full gain range.

Key Specifications

Pinout & Package

AD604ARZ-RL is housed in a 24-lead SOIC (Small Outline Integrated Circuit) package with standard 0.3-inch body width and 1.27 mm pitch, rated for −40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar variable gain amplifier applications.

Compared with AD8367ARUZ and VCA824ID, the AD604ARZ-RL uniquely combines dual-channel matching, 0.8 nV/√Hz noise, and DSX-based linear-in-dB control-making it irreplaceable for high-fidelity ultrasound TGC where inter-channel coherence and SNR preservation are non-negotiable.

Availability

AD604ARZ-RL is available at Aetrix Electronics and suitable for ultrasound imaging systems, high-dynamic-range test instrumentation, medical diagnostic equipment, and industrial NDT equipment requiring stable component supply and long-term obsolescence management.

Supply support for AD604ARZ-RL 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.

The AD604ARZ-RL belongs to the AD60x family of precision variable gain amplifiers, engineered specifically for time-gain control in medical ultrasound and demanding low-noise, wideband signal conditioning applications.

FAQ

What is the maximum gain range achievable per channel of the AD604ARZ-RL?

The AD604ARZ-RL supports two user-selectable gain ranges per channel: 0 dB to 48 dB (with 14 dB preamplifier gain) or 6 dB to 54 dB (with 20 dB preamplifier gain). These ranges are set by configuring FBKx connections and are guaranteed over the full −40°C to +85°C operating temperature range. The AD604ARZ-RL achieves this using an internal R-1.5R ladder attenuator and fixed-gain active feedback amplifier.

Does the AD604ARZ-RL require external components to operate as a complete VGA?

Yes, the AD604ARZ-RL requires external passive components for full functionality: 0.1 µF decoupling capacitors on VREF and VOCM pins, supply bypassing (typically 10 µF + 0.1 µF per rail), and optional resistors to set preamplifier gain (e.g., shorting FBK1 to PAO1 for 14 dB). No external active circuitry is needed-the AD604ARZ-RL drives ADCs directly with its 2.5 V ± 1.5 V output swing.

How does the AD604ARZ-RL achieve ultralow input voltage noise of 0.80 nV/√Hz?

The AD604ARZ-RL achieves 0.80 nV/√Hz input voltage noise through a proprietary preamplifier topology using matched on-chip resistors and optimized transistor sizing. This noise figure is measured at 14 dB preamp gain, RS = 0 Ω, and is maintained across temperature due to internal trimming. The DSX attenuator stage contributes negligible additional noise, preserving the preamp's ultralow-noise performance at the final output.

Can both channels of the AD604ARZ-RL be cascaded for extended gain range?

No-cascading both channels of the AD604ARZ-RL is not recommended. While the datasheet notes that one channel's preamplifier output (PAOx) can feed another device, internal cascading introduces instability and degrades noise performance. For >48 dB gain, Analog Devices recommends using the AD604ARZ-RL's PAOx output to drive a second AD60x-family VGA without a preamplifier (e.g., AD603) to avoid noise accumulation and bandwidth reduction.

What is the purpose of the COM1 and COM2 pins on the AD604ARZ-RL?

The COM1 and COM2 pins on the AD604ARZ-RL provide hardware-level preamplifier shutdown: tying either pin to VPOS disables its respective preamplifier stage, reducing quiescent current and isolating the input path. This feature enables rapid channel muting in phased-array ultrasound systems without relying on VGN control timing, and is electrically distinct from the VGN-driven power-down mode.