Texas Instruments LMH6515SQX/NOPB

Overview

LMH6515SQX/NOPB from Texas Instruments is a 600 MHz digitally controlled variable gain amplifier (DVGA) with precise 1 dB gain steps, 31 dB adjustable range, and fully differential signal path. It features 200 Ω input impedance, selectable 200 Ω/400 Ω output load, and 5 ns gain step switching - optimized for driving high-performance ADCs in IF sampling receivers and cellular base station signal chains.

For engineers reviewing the LMH6515SQX/NOPB datasheet, LMH6515SQX/NOPB pinout, LMH6515SQX/NOPB application, or LMH6515SQX/NOPB equivalent, key selection criteria include OIP3 performance at 75–250 MHz, noise figure (8.3 dB), gain step accuracy (<0.07 dB error at 150 MHz), and WQFN-16 thermal management under 107 mA supply current.

Technical Context

The LMH6515SQX/NOPB integrates a digitally controlled 31-step attenuator (0 to −31 dB) followed by an ultra-linear transconductor stage (0.1 A/V) with on-chip 200 Ω or 400 Ω differential loads. Its open-collector output architecture requires external inductive biasing to set common-mode voltage and enable full 5.6 VPP differential swing.

Gain control uses parallel 5-bit CMOS-compatible inputs (GAIN_0 to GAIN_4) with latch-enabled update timing; internal digital latches store gain settings, and bandwidth remains stable across all gain steps due to architecture-level decoupling of attenuation and amplification stages.

Key Specifications

Pinout & Package

LMH6515SQX/NOPB is housed in a 4 mm × 4 mm, 16-pin thermally enhanced WQFN package with exposed thermal pad (GND). Pinout supports differential analog I/O, parallel 5-bit digital gain control, latch synchronization, and dual power domains (VCC for core, inductive bias for outputs).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digitally controlled variable gain amplifier applications.

Compared with ADL5330ACPZ-R7 and MAX19723ETX+, the LMH6515SQX/NOPB delivers superior gain step fidelity (<0.07 dB error), lower noise figure (8.3 dB vs. ≥9.5 dB), and simpler parallel control - making it optimal for cost-sensitive, high-linearity IF sampling systems operating below 600 MHz.

Availability

LMH6515SQX/NOPB is available at Aetrix Electronics and suitable for cellular infrastructure, instrumentation, IF receiver, and differential line receiver applications requiring stable component supply, long-term manufacturability, and TI-qualified industrial temperature performance.

Supply support for LMH6515SQX/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 with over 50 years of innovation in precision amplifiers and RF components.

The LMH6515SQX/NOPB belongs to TI's high-speed variable gain amplifier product line, engineered specifically for wideband receiver signal chains demanding low noise, high OIP3, and deterministic digital gain control in wireless infrastructure and test equipment.

FAQ

What is the absolute maximum supply voltage for LMH6515SQX/NOPB?

The absolute maximum positive supply voltage (Pin 3, VCC) for LMH6515SQX/NOPB is 5.5 V. Operation above 5.25 V is outside the specified operating range and may cause parametric shift or reliability risk. The output pins (OUT+, OUT−) tolerate up to 6.8 V, but only when biased via external inductors - never apply >5.25 V directly to VCC.

How does LMH6515SQX/NOPB achieve 5 ns gain switching time?

LMH6515SQX/NOPB achieves 5 ns gain step settling through a segmented attenuator architecture that decouples digital switching from analog amplification. The 5-bit gain control directly modulates a highly linear MOSFET-based attenuator stage, while the downstream transconductor operates at fixed bias - eliminating large-signal slewing delays typical in conventional VGAs.

Can LMH6515SQX/NOPB drive a 50 Ω load directly?

No - LMH6515SQX/NOPB is not designed for direct 50 Ω termination. Its output stage is open-collector with internal 200 Ω or 400 Ω loads; connecting a 50 Ω external load creates an effective parallel impedance (~40 Ω), degrading OIP3 and increasing distortion. For 50 Ω systems, use an external 200 Ω:50 Ω matching network or select a 50 Ω-compatible VGA like ADL5330.

What is the role of the LOAD+ and LOAD− pins on LMH6515SQX/NOPB?

LOAD+ (Pin 13) and LOAD− (Pin 16) provide access to internal 200 Ω pull-up resistors tied to OUT+ and OUT−. Leaving both pins floating configures the device for 400 Ω differential load (high-gain mode). Shorting LOAD+ to LOAD− selects 200 Ω mode (low-gain, high-bandwidth), reducing net gain by ~6 dB while improving bandwidth and output drive capability.

Does LMH6515SQX/NOPB support DC-coupled input operation?

Yes - LMH6515SQX/NOPB supports DC-coupled inputs when the external input common-mode voltage is actively driven within 0.9 V to 2.0 V. The internal self-bias is 1.4 V; deviation beyond this range increases distortion. For pure AC-coupled operation, capacitive coupling to ground on IN− is recommended to preserve common-mode rejection and simplify design.