Texas Instruments OPA4684IDR

Overview

OPA4684IDR from Texas Instruments is a quad, low-power, current-feedback operational amplifier optimized for wideband video and signal conditioning applications. It delivers 170MHz bandwidth at G = +2, 120mA output current per channel, and < –78dBc harmonic distortion at 5MHz - enabling high-fidelity broadcast video drivers and ADC input interfaces operating on ±5V or single +5V supplies.

For engineers reviewing the OPA4684IDR datasheet, OPA4684IDR pinout, OPA4684IDR application, or OPA4684IDR equivalent, key selection considerations include its CFBPLUS architecture with linearized inverting-input impedance, minimal bandwidth variation across gain (G = +1 to +20), ±4VPP output swing on ±5V, and SO-14 package compatibility with industrial temperature range (–40°C to +85°C).

Technical Context

The OPA4684IDR implements a patented CFBPLUS architecture featuring an internally closed-loop input buffer stage that linearizes inverting-input impedance (~5Ω), decoupling bandwidth and distortion performance from gain-setting resistor variations. This enables stable 0.1dB gain flatness up to 19MHz at G = +2 and supports peaking elements and multichannel summing without bandwidth collapse.

It operates from dual ±2.5V to ±6V or single +2.8V to +12V supplies, with supply-independent biasing ensuring consistent AC performance across voltage ranges. Its transimpedance open-loop gain is 355kΩ (min), and closed-loop output impedance is 6mΩ at 100kHz - critical for driving 50Ω/75Ω video lines and ADC inputs with minimal signal degradation.

Key Specifications

Pinout & Package

OPA4684IDR is housed in a 14-pin SOIC (SO-14) package (package code D), rated for –40°C to +85°C operation, with θJA = 100°C/W. Pinout is identical across all four channels in quad configuration.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar current-feedback amplifier applications.

Compared with OPA2684IDR, OPA4684IDR provides two additional matched channels in the same footprint-per-channel ratio, enabling compact quad video routing; versus OPA691U, it trades raw speed for 86% lower power and superior thermal efficiency in multichannel embedded systems.

Availability

OPA4684IDR is available at Aetrix Electronics and suitable for broadcast video drivers, ADC input interfaces, and SAW filter post-amplifiers requiring stable component supply, long-term industrial temperature support (–40°C to +85°C), and SO-14 leaded package compatibility.

Supply support for OPA4684IDR 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and high-reliability ICs, with decades of expertise in precision amplifiers and signal chain solutions.

The OPA4684IDR belongs to TI's CFBPLUS current-feedback op amp family, designed specifically for low-power, wideband applications where gain stability, distortion performance, and supply flexibility are critical - including studio video, medical imaging, and high-resolution data acquisition.

FAQ

What supply voltages does the OPA4684IDR support?

The OPA4684IDR supports dual supplies from ±2.5V to ±6V and single supplies from +2.8V to +12V. At ±5V, it delivers full 170MHz bandwidth and ±120mA output drive; at +5V, bandwidth reduces to 110MHz (min) with 80mA sourcing capability. The internal biasing remains stable across this range, ensuring consistent offset and distortion performance without external recalibration.

How does the CFBPLUS architecture improve bandwidth stability in the OPA4684IDR?

The OPA4684IDR's CFBPLUS architecture uses an internally closed-loop input buffer to linearize the inverting-input impedance to ~5Ω, decoupling bandwidth from gain-setting resistor values. This allows bandwidth to remain nearly constant from G = +1 (250MHz) to G = +20 (95MHz), unlike conventional CFB amps where bandwidth drops sharply with gain - enabling predictable design of equalizing filters and multichannel summing circuits.

Can the OPA4684IDR drive 50Ω transmission lines directly?

Yes - the OPA4684IDR delivers ±120mA per channel and supports >±3V swing into 50Ω loads on ±5V supplies. Its closed-loop output impedance is just 6mΩ at 100kHz, minimizing mismatch loss and reflections. For optimal 50Ω matching, use series termination at the output (e.g., 45Ω resistor) with the load grounded, or configure as a doubly-terminated line using 50Ω source and load impedances.

What is the input voltage range for single-supply operation of the OPA4684IDR?

On +5V supply, the OPA4684IDR's input common-mode range extends from 1.25V to 3.75V (min), providing 2.5VPP usable swing centered at 2.5V. This is achieved via external resistive biasing (e.g., 10kΩ divider) at the noninverting input. The 1.25V headroom requirement allows robust AC-coupled video or sensor signal interfacing without clipping at either rail.

Is the OPA4684IDR pin-compatible with other TI quad CFB amplifiers?

The OPA4684IDR shares the same SO-14 pinout as OPA3684 (TSSOP-14 variant) and OPA4658, but not with OPA695 or OPA2691 families. Its pin mapping - including dedicated +V (pin 4), –V (pin 8), and channel-aligned I/O (pins 1–3, 5–7, 9–11, 13–14) - is consistent across TI's D-package quad CFB amplifiers, enabling drop-in replacement where bandwidth, drive, and quiescent current requirements align.