Analog Devices Inc. AD8338ACPZ-R7

Overview

AD8338ACPZ-R7 from Analog Devices is a low-power, fully differential variable gain amplifier (VGA) with 0 dB to 80 dB linear-in-dB gain control, 18 MHz bandwidth, 4.5 nV/√Hz input-referred noise at 80 dB gain, and integrated offset correction and automatic gain control (AGC) functions - designed for ultrasonic receivers, inductive telemetry front ends, and ADC driver compression stages.

For engineers reviewing the AD8338ACPZ-R7 datasheet, AD8338ACPZ-R7 pinout, AD8338ACPZ-R7 application, or AD8338ACPZ-R7 equivalent, key selection criteria include its voltage-controlled gain slope (12.5 mV/dB), differential output swing (2.8 V p-p), 3 mm × 3 mm LFCSP-16 package, and dual-input architecture supporting both voltage- and current-driven configurations.

Technical Context

The AD8338ACPZ-R7 implements an input-variable-gain architecture with a hyperbolic current-controlled VGA core, enabling constant 18 MHz −3 dB bandwidth across its full 80 dB gain range. Its linear-in-dB gain interface uses a 0.1 V to 1.1 V GAIN pin voltage to set gain with ±2 dB accuracy, while MODE pin inversion allows either increasing or decreasing gain vs. control voltage.

It integrates three functional subsystems: (1) offset null circuitry using OFSN–VREF capacitor-based auto-zeroing with programmable high-pass corner; (2) AGC loop with DETO current output and VAGC–VREF rms target setting; and (3) internal 1.5 V reference (VREF) biasing all critical analog nodes including INPR/INMR, OUTP/OUTM, and FBKP/FBKM.

Key Specifications

Pinout & Package

AD8338ACPZ-R7 is housed in a RoHS-compliant, thermally enhanced 3 mm × 3 mm, 16-lead LFCSP package with exposed pad (EPAD) requiring connection to quiet analog ground for optimal noise and thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD8338ACPZ-R7, AD8370ACPZ-R7 trades AGC/offset functionality for RF bandwidth and higher power, while VCA824IPWPR offers comparable gain control but demands external support circuitry - making AD8338ACPZ-R7 uniquely optimized for low-power, self-contained analog front ends in ultrasonic and telemetry systems.

Availability

AD8338ACPZ-R7 is available at Aetrix Electronics and suitable for ultrasonic signal receivers, inductive telemetry front ends, and ADC driver compression stages requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for AD8338ACPZ-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, serving precision instrumentation, industrial, communications, and healthcare markets since 1965.

The AD8338ACPZ-R7 belongs to Analog Devices' Variable Gain Amplifier product line, engineered specifically for low-noise, low-power, fully differential signal conditioning in sensor interface and data acquisition applications demanding wide dynamic range and integrated calibration features.

FAQ

What is the maximum operating temperature range for the AD8338ACPZ-R7?

The AD8338ACPZ-R7 is specified over the industrial temperature range of −40°C to +85°C. This rating is validated per Analog Devices' Rev. C datasheet, with thermal resistance θJA = 48.75°C/W for the 16-lead LFCSP package. Operation beyond +85°C may cause parametric shift or reliability risk; junction temperature must remain below 150°C under all conditions.

Can the AD8338ACPZ-R7 drive a 50 Ω load differentially?

No - the AD8338ACPZ-R7 is not designed to drive 50 Ω loads directly. Its differential output stage is optimized for high-impedance loads (RL = ∞ per AC specs), delivering 2.8 V p-p into open circuit. Driving 50 Ω would severely compress output swing and degrade distortion/noise. For 50 Ω interfaces, use an external line driver or transformer, or configure the AD8338ACPZ-R7 into current-output mode with appropriate termination.

How does the AD8338ACPZ-R7 achieve constant bandwidth across its 80 dB gain range?

The AD8338ACPZ-R7 achieves constant 18 MHz −3 dB bandwidth by implementing an input-variable-gain architecture: gain is adjusted by modulating the input-stage tail current (ID), not the output-stage transconductance. This preserves the small-signal frequency response of the VGA core and output amplifiers independently of gain setting - a key distinction from output-variable amplifiers that trade bandwidth for gain.

Is the VREF pin on the AD8338ACPZ-R7 intended to be used as a system reference for other components?

No - the VREF pin on the AD8338ACPZ-R7 is an internal 1.5 V reference intended solely to bias the device's own analog nodes (inputs, outputs, feedback paths). It is rated for ≤5 mA output and lacks the stability, accuracy, and drive strength required for external system referencing. Use a dedicated precision reference IC (e.g., ADR4515) for system-level voltage references.

What happens if the OFSN pin is left unconnected on the AD8338ACPZ-R7?

Leaving the OFSN pin unconnected on the AD8338ACPZ-R7 disables the offset correction circuit, resulting in higher dc offset errors - up to ±200 mV at mid-gain - which scale with gain and degrade dynamic range. For dc-coupled operation, OFSN must be tied to COMM; for ac-coupled auto-zeroing, connect a capacitor (e.g., 0.1 µF) between OFSN and VREF. Floating OFSN violates the absolute maximum rating and risks unpredictable behavior.