The LMH5401IRMSR is an ultra-wideband fully differential amplifier that occupies the highest tier of analog signal-chain performance. With an 8 GHz gain-bandwidth product and usable linearity from dc to 2 GHz, it is engineered for applications where the signal of interest spans from baseband to microwave frequencies and where the dynamic range must be preserved across that entire span. The device is optimized for radio frequency (RF), intermediate frequency (IF), and high-speed dc-coupled time-domain applications, including the single-ended-to-differential conversion required when driving gigahertz-class analog-to-digital converters.

The LMH5401IRMSR achieves its exceptional bandwidth through a bipolar process and a fully differential architecture that maintains balanced signal paths from input to output. The slew rate of 17,500 V/µs is the highest in its class, enabling the amplifier to reproduce fast transients without rate-limiting. The input voltage noise of 1.25 nV/√Hz and input current noise of 3.5 pA/√Hz provide a low noise floor for wideband signal acquisition.

The harmonic distortion performance underscores the device's suitability for high-dynamic-range applications. At 100 MHz, the second and third harmonics are –104 dBc and –96 dBc respectively, with a 1 V_PP output into a 200 Ω differential load. At 500 MHz, these degrade gracefully to –80 dBc and –77 dBc. Even at 1 GHz, the device maintains –64 dBc HD2 and –58 dBc HD3, performance that is exceptional for a fully differential amplifier in this frequency range.

The LMH5401IRMSR is optimized for both single-ended-to-differential (SE-DE) and differential-to-differential (DE-DE) operation. This dual-mode capability allows the device to serve as either a balun replacement or a differential gain stage, simplifying signal chain architecture by eliminating the need for external transformers in many applications. A common-mode reference input pin aligns the amplifier output common-mode with the specific input requirements of the target ADC, whether that ADC operates with a 1.2 V, 1.5 V, or 2.0 V common-mode voltage.

The amplifier supports both single-supply operation from 3.3 V to 5 V and dual-supply operation when required. The power-down feature reduces supply current when the amplifier is not active, a useful capability in systems that multiplex a single high-speed ADC across multiple input channels. The 14-pin UQFN package measures only 2.5 mm × 2.5 mm, minimizing board area in densely packed RF and data acquisition layouts.

The LMH5401IRMSR is deployed in signal chains where the analog bandwidth requirement exceeds what conventional fully differential amplifiers can provide. Its primary application is as an ADC driver for gigahertz-class data converters, including GSPS (gigasample per second) ADCs used in oscilloscopes, spectrum analyzers, and wideband software-defined radio receivers.

In RF and IF signal chains, the device serves as a gain block for intermediate frequency stages, a buffer for surface acoustic wave (SAW) filters, and a balun replacement for dc-to-2-GHz single-ended-to-differential conversion. The ability to operate with dc coupling is particularly valuable in time-domain applications such as pulsed radar and time-of-flight systems, where the dc and low-frequency content of the signal carries information.

Wireless infrastructure equipment, including base station receivers and microwave backhaul radios, uses the LMH5401IRMSR to condition signals before digitization. High-speed data acquisition systems in test and measurement instruments rely on the device to preserve signal fidelity from the probe tip to the ADC. Medical imaging systems, including MRI and CT scanners, employ the amplifier in receiver chains where bandwidth and linearity determine image resolution and contrast.

The LMH5401IRMSR is a performance-first amplifier that delivers bandwidth, linearity, and slew rate at levels that enable analog signal chains to keep pace with the fastest available data converters. Its ability to perform single-ended-to-differential conversion without external baluns and its support for dc coupling simplify system architecture while preserving the signal integrity that wideband applications demand. For engineers designing RF, IF, or high-speed time-domain signal chains, the LMH5401IRMSR provides the analog front-end performance necessary to fully utilize the capabilities of modern gigahertz-class ADCs.