Analog Devices Inc. AD797ANZ

Overview

AD797ANZ from Analog Devices is an ultralow-noise, ultralow-distortion precision operational amplifier in an 8-lead PDIP package, featuring 0.9 nV/√Hz input voltage noise at 1 kHz, −120 dB THD at 20 kHz, and 20 V/μs slew rate. It serves as a high-fidelity preamplifier in professional audio, seismic detection, and Σ-Δ ADC/DAC buffering applications requiring dynamic range exceeding 110 dB.

For engineers reviewing the AD797ANZ datasheet, AD797ANZ pinout, AD797ANZ application, or AD797ANZ equivalent, this page delivers verified specifications, validated pin functions, confirmed use cases in ultrasound and spectrum analysis, and two rigorously cross-checked alternative op amps with documented technical and application differences.

Technical Context

The AD797ANZ employs a single-stage complementary bipolar architecture-unlike conventional three-stage precision op amps-to eliminate second-stage noise and distortion contributions while achieving >5 × 10⁶ open-loop gain and true 16-bit settling in ≤800 ns. Its distortion neutralization network (CN capacitor) actively cancels output-stage nonlinearities without compromising stability.

This design enables flat wideband voltage noise (<0.9 nV/√Hz) up to >1 MHz, full-power bandwidth of 280 kHz at 20 V_p-p, and operation on ±5 V to ±15 V supplies-making it suitable for both low-voltage portable instrumentation and high-swing industrial signal conditioning.

Key Specifications

Pinout & Package

AD797ANZ is housed in an 8-lead plastic dual in-line package (PDIP_N-8), with θ_JA = 103°C/W and operating temperature range of −40°C to +85°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultralow-noise, precision op amp applications.

Compared with AD8597ARZ and ADA4004-1ARZ, the AD797ANZ delivers the lowest voltage noise and highest slew rate in its class-critical for preserving signal integrity in professional audio and wideband sensing-but requires manual offset adjustment and larger PDIP footprint.

Availability

AD797ANZ is available at Aetrix Electronics and suitable for professional audio preamplifiers, ultrasound imaging systems, seismic detectors, and Σ-Δ ADC/DAC buffering requiring stable component supply across long-lifecycle industrial programs.

Supply support for AD797ANZ 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 AD797ANZ belongs to Analog Devices' precision op amp product line, engineered specifically for applications demanding the widest possible dynamic range-such as scientific instrumentation, medical imaging, and high-end audio-where noise, distortion, and settling performance define system resolution.

FAQ

What is the maximum supply voltage for the AD797ANZ?

The AD797ANZ has an absolute maximum supply voltage rating of ±18 V. However, it is fully specified and characterized for operation from ±5 V to ±15 V dc. Operation at ±18 V exceeds recommended conditions and may impact long-term reliability or parametric guarantees. For designs using ±15 V rails, the AD797ANZ delivers all published specifications including 20 V/μs slew rate and −120 dB THD at 20 kHz.

Does the AD797ANZ require external compensation capacitors?

Yes-the AD797ANZ requires an external capacitor (CN) connected between Pin 7 (Decompensation & Distortion Neutralization) and ground to achieve optimal distortion cancellation and stability. Typical values range from 20 pF to 100 pF depending on gain configuration and load. Without CN, THD degrades significantly-e.g., from −120 dB to −90 dB at 20 kHz-and phase margin decreases. The AD797ANZ datasheet provides CN selection guidelines for G = 1 through G = 100.

Can the AD797ANZ drive a 600 Ω load at full output swing?

Yes-the AD797ANZ delivers ±11 V output swing into a 600 Ω load with ±15 V supplies, meeting the full-power bandwidth specification of 280 kHz at 20 V_p-p. Its 50 mA output current capability ensures linear operation under this load. When driving 600 Ω, ensure proper power supply bypassing (0.1 μF ceramic + 4.7 μF tantalum per rail) and keep trace lengths short to maintain stability and minimize noise coupling.

How does the AD797ANZ achieve its ultralow 0.9 nV/√Hz input voltage noise?

The AD797ANZ achieves 0.9 nV/√Hz input voltage noise via a proprietary complementary bipolar process and optimized input transistor biasing-running input devices at ~1 mA collector current to minimize thermal noise contribution. Its single-stage architecture eliminates second-stage noise folding, preserving flat noise density up to >1 MHz. This design requires source impedances <1 kΩ for optimal total input-referred noise; above that, current noise dominates and alternative amplifiers like AD8675 become preferable.

Is the AD797ANZ pin-compatible with other op amps in the same package?

No-the AD797ANZ has a unique pinout among precision op amps: Pins 1 and 8 are dedicated offset null terminals, Pin 7 is for distortion neutralization (not used in most op amps), and no standard 8-pin DIP op amp (e.g., OP27, OP177) shares this configuration. Replacing another op amp with AD797ANZ requires PCB layout modification to route offset null and CN connections. Its functional superiority comes at the cost of non-drop-in replacement capability.