Texas Instruments OPA404AG

Overview

OPA404AG from Texas Instruments (formerly Burr-Brown) is a quad high-speed precision dielectrically isolated FET (Difet®) operational amplifier in a 14-pin ceramic DIP package, rated for –25°C to +85°C operation. It delivers 6.4 MHz gain bandwidth, 35 V/µs slew rate, ±750 µV max input offset voltage, ±4 pA max input bias current, and 1.5 µs settling time to 0.01%, enabling high-accuracy signal conditioning in ultrasound front-ends and photodiode amplifiers.

For engineers reviewing the OPA404AG datasheet, OPA404AG pinout, OPA404AG application, or OPA404AG equivalent, key selection criteria include its ultra-low bias current stability over common-mode voltage, laser-trimmed offset for <±260 µV typical drift, cascode input architecture preserving speed without sacrificing DC precision, and standard quad DIP pin compatibility for drop-in upgrades of legacy BIFET designs.

Technical Context

The OPA404AG employs a dielectrically isolated FET (Difet®) input stage with cascode topology, decoupling gate-to-drain voltage dependence to maintain ±4 pA max bias current across ±10.5 V common-mode range. Its laser-trimmed thin-film resistors achieve ±260 µV typical input offset and ±3 µV/°C drift - the lowest in quad FET op amps at introduction.

Unity-gain stable with 1000 pF load capacitance tolerance, the OPA404AG supports high closed-loop bandwidths (e.g., 570 kHz full-power response at 20 V_p-p) while retaining 0.01% settling in 1.5 µs under 10 V step conditions - critical for fast data acquisition and precision pulse amplification.

Key Specifications

Pinout & Package

OPA404AG is housed in a 14-pin ceramic dual in-line package (CDIP SB, package drawing JD), rated for –25°C to +85°C ambient operation and featuring hermetic sealing for high-reliability applications including medical and aerospace systems.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad precision op amp applications.

Compared with OPA404AG, OPA4134UA trades ultra-low bias current for higher bandwidth and surface-mount convenience, while LMC6084IMX sacrifices speed to achieve femtoamp-level input leakage - making OPA404AG uniquely balanced for high-speed, high-impedance, high-reliability applications requiring hermetic packaging.

Availability

OPA404AG is available at Aetrix Electronics and suitable for precision instrumentation, medical equipment, and ultrasonic imaging systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for OPA404AG 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 acquired Burr-Brown Corporation in 2000 and maintains its precision analog portfolio, known for high-performance op amps, data converters, and interface ICs serving industrial, medical, and test equipment markets.

The OPA404AG belongs to TI's legacy high-precision Difet® op amp family, engineered specifically for applications demanding simultaneous low input bias current, wide bandwidth, and laser-trimmed DC accuracy - such as detector arrays and professional audio signal chains.

FAQ

What is the maximum operating temperature range for the OPA404AG?

The OPA404AG is specified for operation from –25°C to +85°C ambient temperature. Its ceramic DIP package provides superior thermal stability versus plastic alternatives, and the internal design maintains ±4 pA max input bias current and ±750 µV max offset voltage across this full range - critical for medical and industrial deployments where ambient conditions vary significantly. The OPA404AG also supports storage from –65°C to +150°C.

Does the OPA404AG require external offset nulling circuitry?

No, the OPA404AG does not require external offset nulling. Its laser-trimmed thin-film resistors deliver ±260 µV typical input offset voltage and ±3 µV/°C drift - the lowest in quad FET op amps at time of release. Figure 1 in the datasheet shows optional trim circuitry only for applications needing sub-100 µV offset; most precision instrumentation, ultrasound, and photodiode designs operate within spec using the OPA404AG as-is.

Can the OPA404AG drive capacitive loads without oscillation?

Yes, the OPA404AG is stable driving up to 1000 pF capacitive loads in unity-gain configuration, as confirmed in the "Load Capacitance Stability" specification. This eliminates the need for external series resistance or compensation networks when driving ADC input filters, coaxial cables, or multiplexer outputs - simplifying layout and improving signal integrity in high-speed data acquisition systems using the OPA404AG.

How does the OPA404AG's cascode input stage improve performance over standard BIFET op amps?

The OPA404AG's cascode input stage isolates the FET gate from drain voltage variations, preventing the exponential rise in bias current seen in conventional BIFET amplifiers (e.g., LF156) as common-mode voltage increases. As shown in Figure 4, OPA404AG maintains <±4 pA bias current across ±10.5 V common-mode range, whereas LF156 exceeds 50 pA at ±10 V - directly enabling stable high-impedance transimpedance gains and accurate DC-coupled measurements with the OPA404AG.

Is the OPA404AG pin-compatible with older quad op amps like the LM348?

Yes, the OPA404AG uses the industry-standard 14-pin DIP pinout defined for quad op amps, matching LM348, LF347, and TL084. Pin 1 is Output A, Pin 2 is –In A, Pin 3 is +In A, Pin 4 is +VCC, etc. This allows direct socket replacement in existing designs - upgrading bandwidth from ~1 MHz (LM348) to 6.4 MHz and bias current from ~30 nA to ±4 pA - without PCB modification, making the OPA404AG ideal for performance-critical field upgrades.