Analog Devices Inc. LTC6268HS8-10#PBF

Overview

LTC6268HS8-10#PBF from Analog Devices (formerly Linear Technology) is a single-channel, decompensated FET-input operational amplifier optimized for ultra-low input bias current (±3 fA typ. at 25°C), 4 GHz gain-bandwidth product, and 0.45 pF common-mode input capacitance. It operates from 3.1V to 5.25V, delivers rail-to-rail output swing, and is gain-of-10 stable-making it ideal for high-speed transimpedance amplifiers in photodiode and photomultiplier tube signal chains.

For engineers reviewing the LTC6268HS8-10#PBF datasheet, LTC6268HS8-10#PBF pinout, LTC6268HS8-10#PBF application, or LTC6268HS8-10#PBF equivalent, key selection criteria include femtoamp-level input bias current stability over temperature, sub-picofarad input capacitance for wideband TIA design, shutdown functionality with 360 ns turn-on time, and SO-8 package compatibility with guard-ring layout techniques to suppress board leakage.

Technical Context

The LTC6268HS8-10#PBF employs a CMOS input buffer stage that bootstraps protection diodes to minimize input leakage, paired with a complementary differential input stage covering full input voltage range (–0.1 V to 4.5 V). Its decompensated architecture requires minimum noise gain of 10 for stability, enabling high closed-loop bandwidth in transimpedance configurations.

It integrates active low-power shutdown (SHDN pin, 0.75 V logic threshold), supports split supplies (e.g., ±2.5 V), and features rail-to-rail output driven by common-emitter output transistors. Input-referred voltage noise is 4.0 nV/√Hz at 1 MHz, and current noise is 7 fA/√Hz at 100 kHz-critical for low-noise, high-impedance sensor interfacing.

Key Specifications

Pinout & Package

The LTC6268HS8-10#PBF is housed in an 8-lead plastic SOIC (SO-8) package with two unconnected pins (Pin 5 and Pin 8) designated for guard-ring implementation to reduce PCB surface leakage into high-impedance inputs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-bias-current, high-speed op amp applications.

Compared with ADA4817-1ARMZ-R7 and LTC6268IS8-10#PBF, the LTC6268HS8-10#PBF uniquely combines 4 GHz bandwidth, ±3 fA bias current, integrated shutdown, and –40°C to +125°C qualification-enabling robust, high-fidelity optical front-ends in demanding thermal and power-constrained environments.

Availability

LTC6268HS8-10#PBF is available at Aetrix Electronics and suitable for photodiode transimpedance amplifiers, photomultiplier post-amplifiers, and low-IBIAS sensor interfaces requiring stable component supply across industrial, test & measurement, and medical OEM programs.

Supply support for LTC6268HS8-10#PBF 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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies.

The LTC6268 family was designed specifically for ultra-low-noise, ultra-low-bias-current, high-speed amplification in optical sensing, scientific instrumentation, and precision measurement systems.

FAQ

What is the maximum operating temperature specification for the LTC6268HS8-10#PBF?

The LTC6268HS8-10#PBF is fully specified over the –40°C to +125°C junction temperature range, with absolute maximum junction temperature rated at 150°C. This H-grade qualification makes it suitable for under-hood automotive, industrial motor control, and high-ambient-temperature instrumentation applications where thermal derating margins are critical.

Does the LTC6268HS8-10#PBF require external compensation for stability in gain-of-10 configurations?

No, the LTC6268HS8-10#PBF is internally decompensated for gain-of-10 stability and does not require external compensation components when configured with noise gain ≥10. However, in transimpedance amplifier applications, a small feedback capacitor (C_F) is still required for phase margin optimization-e.g., 60 fF for 20 kΩ R_F and 1 pF total input capacitance-as detailed in the Applications Information section of the datasheet.

How does the guard-ring capability of the LTC6268HS8-10#PBF's SO-8 package improve performance?

The LTC6268HS8-10#PBF's SO-8 package includes two unconnected pins (Pins 5 and 8) explicitly intended for PCB guard-ring routing around the +IN and –IN traces. This guard ring, held at the same potential as the inputs (e.g., via unity-gain follower), reduces surface leakage currents on the PCB-critical for preserving femtoamp-level input bias current accuracy, especially in humid or contaminated environments.

What is the typical input bias current of the LTC6268HS8-10#PBF at 125°C?

The typical input bias current of the LTC6268HS8-10#PBF at 125°C is ±3 fA, with a maximum guaranteed value of 4 pA over the full –40°C to +125°C operating range. This extreme stability across temperature distinguishes it from most JFET or CMOS op amps, whose I_B increases exponentially with junction temperature.

Can the LTC6268HS8-10#PBF operate from split supplies such as ±2.5 V?

Yes, the LTC6268HS8-10#PBF supports split-supply operation, including ±2.5 V, as long as the total supply voltage (V+ – V–) remains within 3.1 V to 5.25 V. The input common-mode range extends from V– to V+ – 0.5 V, and the rail-to-rail output swings within 140 mV of each rail at 10 mA load-making it well-suited for bipolar signal conditioning in precision analog front-ends.