Texas Instruments LMH6515SQ/NOPB

Overview

LMH6515SQ/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 on-chip 200 Ω or 400 Ω selectable output impedance, 8.3 dB noise figure, and 5 ns gain step settling time-designed to drive high-performance ADCs in IF sampling receivers and cellular base station signal chains.

For engineers reviewing the LMH6515SQ/NOPB datasheet, LMH6515SQ/NOPB pinout, LMH6515SQ/NOPB application, or LMH6515SQ/NOPB equivalent, key selection criteria include differential input/output compatibility, 200 Ω input impedance, gain-step linearity across temperature, OIP3 performance at 75–250 MHz, and WQFN-16 thermal management under 107 mA supply current.

Technical Context

The LMH6515SQ/NOPB integrates a digitally controlled 31-step attenuator (0 to −31 dB) followed by an ultra-linear transconductor stage with 0.1 A/V transconductance. Its open-collector differential outputs require external inductive biasing to set common-mode voltage and enable full 5.6 VPP swing-critical for driving ADCs without clipping.

Gain control uses parallel 5-bit CMOS logic (GAIN_0 to GAIN_4) with latch-enabled hold functionality; switching occurs in 5 ns with ±0.07 dB step error at 150 MHz. Bandwidth scales inversely with effective load: 600 MHz at 100 Ω, 260 MHz at 200 Ω-enabling trade-offs between speed and distortion (OIP3 = 40 dBm @ 75 MHz, 200 Ω load).

Key Specifications

Pinout & Package

LMH6515SQ/NOPB is housed in a thermally enhanced 4 mm × 4 mm, 16-pin WQFN package with exposed thermal pad (θ_JA = 47°C/W). Pin 1 is GAIN_0; pin numbering follows standard top-view orientation with GND pins at 5, 8 and thermal pad internally connected to ground.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADL5330ACPZ-R7 and MAX19707ETX+, the LMH6515SQ/NOPB delivers superior gain-step accuracy (±0.07 dB), faster digital switching (5 ns vs. µs-scale), and flexible load-selectable output impedance-making it optimal for high-fidelity IF sampling where deterministic digital control and distortion-limited performance are critical.

Availability

LMH6515SQ/NOPB is available at Aetrix Electronics and suitable for cellular base stations, IF sampling receivers, instrumentation, and differential line receiver applications requiring stable component supply, consistent parametric performance across temperature, and long-term production continuity.

Supply support for LMH6515SQ/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, communications, and automotive markets.

The LMH6515SQ/NOPB belongs to TI's high-speed amplifier portfolio, engineered specifically for digitally controlled gain applications in RF and IF signal paths-emphasizing linearity, low noise, and fast settling for ADC interface and automatic gain control systems.

FAQ

What is the absolute maximum supply voltage for LMH6515SQ/NOPB?

The absolute maximum positive supply voltage (Pin 3, VCC) for LMH6515SQ/NOPB is 5.5 V. Operation above 5.25 V is outside the specified operating range and may degrade performance or reliability. The output pins (OUT+, OUT−) tolerate up to 6.8 V, enabling voltage swings beyond VCC when using RF choke biasing-this is intentional and required for full 5.6 VPP differential output swing.

How does LMH6515SQ/NOPB achieve 1 dB gain steps with such low error?

LMH6515SQ/NOPB achieves ±0.02 dB typical gain step error at DC and ±0.07 dB at 150 MHz through laser-trimmed thin-film attenuator elements and a highly linear transconductor stage. The on-chip 5-bit digital attenuator uses binary-weighted resistor networks with matched layout and process compensation-ensuring monotonicity and cumulative error < ±0.4 dB across all 32 gain states.

Can LMH6515SQ/NOPB accept single-ended input signals?

Yes, LMH6515SQ/NOPB supports single-ended input operation: connect the signal to IN+ (Pin 6) and capacitively couple IN− (Pin 7) to ground. The internal 200 Ω input impedance remains valid, and self-biasing at 1.4 V allows ±1.4 V AC-coupled input swing. For larger signals, externally bias IN− to shift common-mode voltage-though distortion increases slightly above 2.0 V.

What is the purpose of LOAD+ and LOAD− pins on LMH6515SQ/NOPB?

LOAD+ (Pin 13) and LOAD− (Pin 16) configure the internal output load network. Leaving both pins floating enables the 400 Ω differential load option (higher gain, lower bandwidth). Shorting LOAD+ to LOAD− selects the 200 Ω option (lower gain, 600 MHz bandwidth). This hardware-selectable mode eliminates need for external resistors and optimizes trade-offs between gain, bandwidth, and OIP3 without changing PCB layout.

Does LMH6515SQ/NOPB require external inductors on its outputs?

Yes, LMH6515SQ/NOPB's open-collector outputs require external RF chokes (e.g., 44.3 nH) tied to 5 V to establish output common-mode voltage and enable full differential swing. Without inductors, the output transistors saturate due to internal 200 Ω pull-up resistors. Inductor value affects bandwidth and filtering-TI recommends resonant tuning with ADC input capacitance for optimal IF response in reference designs like ADC14V155KDRB.