Texas Instruments LMH6554LE/NOPB

Overview

LMH6554LE/NOPB from Texas Instruments is a 2.8-GHz ultra-linear fully differential amplifier optimized as a high-fidelity ADC driver for 14–16-bit data acquisition systems. It delivers 1.8-GHz large-signal bandwidth at 2 V_PP, −96 dBc HD2/−97 dBc HD3 at 75 MHz, and 0.9 nV/√Hz input voltage noise - enabling precision IF/RF gain blocks and single-ended-to-differential conversion in automotive safety and video-over-twisted-pair systems.

For engineers reviewing the LMH6554LE/NOPB datasheet, LMH6554LE/NOPB pinout, LMH6554LE/NOPB application, or LMH6554LE/NOPB equivalent, key selection criteria include its current-feedback architecture, 14-pin UQFN package with dual supply rails (±2.5 V), VCM-controlled output common-mode setting, enable functionality (VEN), and verified 16-bit linearity up to 75 MHz into 200-Ω loads.

Technical Context

The LMH6554LE/NOPB implements a proprietary differential current-mode input stage that decouples gain and bandwidth - maintaining 2.8-GHz small-signal bandwidth even at AV = 4, with only 1.6-GHz reduction. Its integrated output common-mode control loop forces matched +OUT/−OUT magnitude and phase inversion independent of input common-mode voltage, critical for single-ended-to-differential conversion.

It operates as a current-feedback amplifier (CFA) with 180-kΩ open-loop transimpedance gain, requiring external RF/RG resistor networks for gain setting (e.g., RF = 200 Ω, RG = 91 Ω for AV = 2). Stability relies on precise resistor matching (≤0.1% recommended) to preserve CMRR (>82 dB), output balance error (−64 dB), and distortion performance across frequency.

Key Specifications

Pinout & Package

The LMH6554LE/NOPB is housed in a 2.50 mm × 2.50 mm, 14-lead UQFN (NHJ) package with wettable flanks and thermal pad. Pin 1 is marked by a dot; pins are numbered counterclockwise. The exposed thermal pad must be soldered to PCB ground for thermal management (R_θJA = 60 °C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fully differential amplifier applications.

Compared with THS4561IRGT and ADA4940-1ACPZ-R7, the LMH6554LE/NOPB uniquely combines 2.8-GHz small-signal bandwidth, integrated VCM control, and −96 dBc HD2 at 75 MHz - making it the only option validated for 16-bit ADC driving up to 75 MHz with transformerless single-ended interface.

Availability

LMH6554LE/NOPB is available at Aetrix Electronics and suitable for high-speed data acquisition, automotive radar signal conditioning, and precision test equipment requiring stable component supply and long-term lifecycle support.

Supply support for LMH6554LE/NOPB 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 and embedded processing technologies, with decades of expertise in high-speed amplifier design and manufacturing.

The LMH6554LE/NOPB belongs to TI's Ultra-High-Speed Fully Differential Amplifier product line, engineered specifically for wideband, low-distortion signal conditioning in data converter interfaces and RF/IF subsystems.

FAQ

What is the recommended power supply configuration for LMH6554LE/NOPB in high-linearity applications?

The LMH6554LE/NOPB achieves optimal distortion performance (−96 dBc HD2 at 75 MHz) under split-supply operation at ±2.5 V. This configuration maximizes input common-mode range and output swing (±1.42 V into 200 Ω), avoids AC-coupling constraints, and improves PSRR to 95 dB. Single 5-V operation is possible but limits usable input range and increases sensitivity to supply ripple.

How does the VCM pin function in LMH6554LE/NOPB, and what happens if left floating?

The VCM pin on the LMH6554LE/NOPB sets the output common-mode voltage with 0.99–1.0 V/V gain. When driven by a low-impedance reference (e.g., 1.2 V for ADCs), it forces +OUT and −OUT to center at that voltage regardless of input CM variation. If left floating, an internal mid-supply bias defaults VCM to (V+ + V−)/2 - but this introduces sensitivity to supply imbalance and degrades output balance error beyond −60 dB.

Can LMH6554LE/NOPB drive a 50-Ω differential load directly, and what are the implications?

No - the LMH6554LE/NOPB is not designed for direct 50-Ω differential termination. Its specified load is 200 Ω differential (100 Ω per side). Driving 50 Ω would exceed output current limits (±150 mA max), cause thermal stress, and degrade distortion (OIP3 drops >5 dB). Use 200-Ω termination with external 1:2 impedance transformation if 50-Ω system interface is required.

What resistor tolerance is required for RF and RG to maintain LMH6554LE/NOPB's published distortion specs?

0.1% tolerance or better is required for RF and RG resistors to maintain the LMH6554LE/NOPB's −96 dBc HD2 specification at 75 MHz. Mismatch >0.2% degrades CMRR and introduces differential-to-common-mode conversion, raising HD2 by ≥6 dB. TI recommends thin-film resistors with matched TC and layout symmetry across both feedback paths.

Does LMH6554LE/NOPB support DC-coupled single-ended-to-differential conversion, and what design precautions apply?

Yes - the LMH6554LE/NOPB supports true DC-coupled single-ended-to-differential conversion via its internal common-mode feedback loop. Critical precautions include: (1) AC-coupling the unused input to prevent input stage saturation, (2) using matched 0.1% RF/RG resistors, (3) bypassing VCM with 0.1 μF ceramic to ground, and (4) routing VCM trace away from noisy supplies to avoid injecting ripple onto outputs.