Texas Instruments LMH6881SQ/NOPB

Overview

LMH6881SQ/NOPB from Texas Instruments is a DC–2.4 GHz programmable differential amplifier optimized for high-linearity signal conditioning in RF/IF gain blocks, ADC drivers, and test equipment front ends. It delivers 26 dB to 6 dB voltage gain in 0.25-dB steps, 44 dBm OIP3 at 100 MHz, 9.7 dB noise figure, and 100 Ω differential input impedance - enabling direct interface with mixers, filters, and 100-Ω transmission lines.

For engineers reviewing the LMH6881SQ/NOPB datasheet, LMH6881SQ/NOPB pinout, LMH6881SQ/NOPB application, or LMH6881SQ/NOPB equivalent, this page provides verified specifications, SPI/parallel gain control timing, thermal performance (RθJA = 38.1°C/W), shutdown behavior, and real-world use cases in spectrum analyzers, oscilloscope front ends, and differential cable drivers - all confirmed against TI's SNOSC72F datasheet (Rev. F, Feb 2015).

Technical Context

The LMH6881SQ/NOPB integrates three functional stages: a low-noise amplifier, digitally controlled attenuator, and low-distortion output buffer - enabling consistent OIP3 and NF across its full 20-dB gain range without external resistors. Its dual-input architecture supports both 100-Ω differential (INPD/INMD) and 50-Ω single-ended (INPS/INMS) sources, with independent common-mode control via OCM pin (gain = 2).

Gain is configurable via parallel interface (2-dB steps, 4-bit D0–D3) or SPI-compatible serial interface (0.25-dB steps, SDI/SDO/CLK/CS). Power-down is supported through dedicated SD pin (logic-high active) or SPI register, reducing supply current from 135 mA to 15 mA. Fabricated in TI's CBiCMOS8 SiGe process, it operates from 4.75 V to 5.25 V with guaranteed −40°C to +85°C performance.

Key Specifications

Pinout & Package

LMH6881SQ/NOPB uses a thermally enhanced 24-pin WQFN package (4.00 mm × 4.00 mm) with exposed thermal pad bonded to ground. Pin layout supports high-frequency layout: four VCC pins (19, 20, 23, 24), four GND pins (6, 7, 12, 13), and symmetric differential I/O routing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMH6882RTWT and ADL5562ACPZ-R7, LMH6881SQ/NOPB uniquely combines programmable 0.25-dB gain control, integrated 100-Ω input, and power-down capability in a single-channel 4-mm WQFN - making it the only option for space-constrained, dynamically reconfigurable RF signal chains requiring both linearity and flexibility.

Availability

LMH6881SQ/NOPB is available at Aetrix Electronics and suitable for oscilloscope front ends, spectrum analyzer gain blocks, and differential ADC driver applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for industrial and test-equipment OEMs.

Supply support for LMH6881SQ/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, embedded processing, and high-performance signal chain solutions for industrial, automotive, and communications markets.

The LMH6881SQ/NOPB belongs to TI's high-speed differential amplifier product line, designed specifically for DC-coupled, wideband gain control in test & measurement, medical imaging, and wireless infrastructure where linearity, noise, and programmability are co-critical.

FAQ

What is the maximum operating frequency and small-signal bandwidth of the LMH6881SQ/NOPB?

The LMH6881SQ/NOPB has a small-signal bandwidth of 2.4 GHz, verified at 2 VPPD output swing into 200 Ω. This bandwidth supports operation up to 2.4 GHz in linear gain applications, including IF stages in 5G FR1 and Wi-Fi 6E systems. Performance remains flat within ±0.5 dB up to 1 GHz and rolls off gradually beyond that, with usable gain extending to 2.4 GHz per TI's SNOSC72F datasheet.

Does the LMH6881SQ/NOPB support both differential and single-ended input configurations?

Yes, the LMH6881SQ/NOPB supports both configurations: differential inputs (INPD/INMD) present a matched 100-Ω impedance, while single-ended inputs (INPS/INMS) accept 50-Ω sources - with the unused input terminated to 50 Ω. This dual-mode capability eliminates external matching networks and simplifies interface design across diverse signal sources like mixers, filters, and cable feeds.

How does gain control work on the LMH6881SQ/NOPB, and what are the step resolutions?

The LMH6881SQ/NOPB supports two gain control modes: parallel (D0–D3 pins, 2-dB steps, 10 discrete settings) and SPI serial (0.25-dB steps, 80 total settings from 6 dB to 26 dB). The SPI interface uses SDI/SDO/CLK/CS pins and requires no external clock source beyond standard MCU SPI peripherals. Both modes retain full linearity and noise performance across the entire gain range.

What is the purpose of the OCM pin on the LMH6881SQ/NOPB, and how is it used?

The OCM (Output Common Mode) pin on the LMH6881SQ/NOPB sets the output common-mode voltage with a gain of 2 - applying 1.25 V yields 2.5 V at the differential outputs. This feature enables precise alignment with ADC reference voltages (e.g., 2.5 V for 5-V-supply SAR or pipeline ADCs) and eliminates need for external level-shifting circuitry in DC-coupled signal chains.

What thermal performance can be expected from the LMH6881SQ/NOPB in a typical PCB layout?

In a standard 4-layer PCB with 2 oz copper and the exposed thermal pad soldered to a solid ground plane, the LMH6881SQ/NOPB achieves RθJA = 38.1°C/W. At full 135 mA supply current (26 dB gain), junction temperature rise is ~5.1°C above ambient - well within the 150°C absolute max. Thermal derating is not required below +85°C ambient, per TI's thermal characterization data in SNOSC72F.