Analog Devices Inc. AD797BRZ

Overview

AD797BRZ from Analog Devices is an ultralow-noise, ultralow-distortion precision operational amplifier designed for high-fidelity signal conditioning in demanding analog front-ends. It delivers 0.9 nV/√Hz input voltage noise at 1 kHz, −120 dB THD at 20 kHz, and 20 V/μs slew rate, making it ideal for microphone preamplifiers, seismic detectors, and Σ-Δ ADC buffers where dynamic range and signal integrity are critical.

For engineers reviewing the AD797BRZ datasheet, AD797BRZ pinout, AD797BRZ application, or AD797BRZ equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative options with documented differences, and supply support tailored for high-reliability analog systems.

Technical Context

The AD797BRZ employs a single-stage ultrahigh-gain bipolar architecture (gain >5 × 10⁶) to eliminate second-stage noise and distortion contributions-unlike conventional three-stage op amps. This enables flat wideband noise (<0.9 nV/√Hz up to >1 MHz) and true 16-bit settling in 800 ns.

Its distortion neutralization circuit uses an external capacitor (CN) to cancel output-stage nonlinearities without affecting stability or frequency response. The amplifier operates across ±5 V to ±15 V supplies, supports ±12 V output swing into 2 kΩ, and maintains 110 MHz gain bandwidth at G = 1000 with 12.5–20 V/μs slew rate.

Key Specifications

Pinout & Package

AD797BRZ is housed in an 8-lead SOIC package (R-8 suffix), with θ_JA = 120°C/W on a 4-layer JEDEC PCB. Pin functions are validated per Figure 2 and Table 2 of Rev. K datasheet.

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 AD797BRZ uniquely combines sub-1 nV/√Hz noise, −120 dB THD, and 16-bit settling in 800 ns-making it irreplaceable in applications demanding simultaneous ultralow noise, ultralow distortion, and high-speed precision.

Availability

AD797BRZ is available at Aetrix Electronics and suitable for professional audio preamplifiers, ultrasound imaging systems, seismic detection equipment, and Σ-Δ ADC/DAC buffering requiring stable component supply across extended product lifecycles.

Supply support for AD797BRZ 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 AD797BRZ 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 capability.

FAQ

What is the maximum supply voltage for the AD797BRZ?

The AD797BRZ has an absolute maximum supply voltage rating of ±18 V. It is fully specified and characterized for operation from ±5 V to ±15 V dc. Operation beyond ±15 V is not recommended for long-term reliability, and thermal dissipation must be verified per θ_JA = 120°C/W for the SOIC package. The AD797BRZ must never be operated with supply voltages exceeding ±18 V, as permanent damage may occur.

Does the AD797BRZ require external compensation components?

Yes-the AD797BRZ includes a dedicated Distortion Neutralization pin (Pin 7) that requires an external capacitor (CN, typically 10–100 pF) to cancel output-stage harmonic distortion. Additionally, a 100 Ω series resistor on the inverting input is recommended for stability in unity-gain follower configurations. These components are mandatory for achieving the −120 dB THD and 800 ns settling performance specified for the AD797BRZ.

Can the AD797BRZ drive a 600 Ω load at full output swing?

Yes-the AD797BRZ delivers ±11 V output swing into a 600 Ω load with ±15 V supplies, and ±2.5 V with ±5 V supplies, per Table 2. Its 50 mA output current capability allows direct driving of 600 Ω loads without external buffers. However, output voltage swing decreases under heavy capacitive loading, and CL compensation per Figure 39 is required to maintain stability and avoid peaking when driving >50 pF.

What is the purpose of the Offset Null pins (1 and 8) on the AD797BRZ?

Pins 1 and 8 on the AD797BRZ are Offset Null terminals used to trim input offset voltage via an external potentiometer (typically 10 kΩ) connected between them, with the wiper grounded. This adjustment reduces the 80 μV maximum V_OS to near-zero, critical for dc-coupled precision applications like seismic detector front-ends. If unused, both pins must be left unconnected-no pull-up/down or bypassing is required.

How does the AD797BRZ achieve its 0.9 nV/√Hz input voltage noise?

The AD797BRZ achieves 0.9 nV/√Hz input voltage noise through a proprietary complementary bipolar (CB) process and optimized input transistor design operating at ~1 mA collector current. Its single-stage architecture eliminates second-stage noise contributions, resulting in flat spectral density from <10 Hz to >1 MHz. This performance is only maintained when source resistance remains below 1 kΩ; above that, current noise dominates, and alternate amplifiers like AD8675 are recommended per Analog Devices' AN-940.