Texas Instruments THS4131CD

Overview

THS4131CD from Texas Instruments is a fully differential input/output amplifier optimized for high-speed, low-noise signal conditioning in precision analog front-ends. It delivers 170 MHz small-signal bandwidth (±15 V supply), 51 V/µs slew rate, –102 dBc THD at 250 kHz, and 1.25 nV/√Hz input voltage noise - enabling high-fidelity differential ADC driving in medical ultrasound and instrumentation systems.

For engineers reviewing the THS4131CD datasheet, THS4131CD pinout, THS4131CD application, or THS4131CD equivalent, key selection criteria include its fully differential architecture, VOCM-controlled output common-mode level, absence of power-down functionality (vs. THS4130), SOIC-8 package thermal performance, and compatibility with ±2.5 V to ±15 V dual supplies or 5–30 V single supplies.

Technical Context

The THS4131CD implements a true fully differential signal path from input to output using TI's high-voltage complementary bipolar process, supporting supply voltages up to ±15 V. Its internal architecture includes matched output buffers, a dedicated VOCM error amplifier, and no internal power-down circuitry - distinguishing it from the THS4130CD variant.

It achieves 95 dB CMRR at 800 kHz and maintains stable operation with differential or single-ended inputs via configurable feedback networks. The device requires external resistor matching (≤1% tolerance) to preserve output balance, minimize HD2 degradation, and sustain specified PSRR (73–98 dB) and CMRR performance across frequency.

Key Specifications

Pinout & Package

THS4131CD is packaged in an 8-pin SOIC (D package) with standard 1.27 mm pitch and exposed thermal pad not present - unlike the HVSSOP variant. This package offers moderate thermal resistance (R_θJA = 126.3°C/W) suitable for continuous 15 mA quiescent current operation at ambient temperatures up to +70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with THS4131ID, THS4131CD trades extended temperature range for lower cost and qualification scope; compared with THS4561IRGET, it sacrifices GHz bandwidth and ultra-low noise for robust ±15 V operation and SOIC-8 manufacturability - making THS4131CD the preferred choice for high-dynamic-range, medium-bandwidth industrial and medical signal chains.

Availability

THS4131CD is available at Aetrix Electronics and suitable for medical ultrasound imaging, high-precision data acquisition, and industrial sensor signal conditioning requiring stable component supply across multi-year production cycles.

Supply support for THS4131CD 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-performance amplifiers and data converter interface solutions.

The THS413x product line was designed specifically for demanding fully differential signal chain applications - including ultrasound, test equipment, and high-speed data acquisition - where low noise, high CMRR, and wide supply range are essential.

FAQ

What is the power-down capability of THS4131CD?

THS4131CD does not include a power-down function. Unlike the THS4130CD variant, which features an active-low PD pin (Pin 7), THS4131CD leaves Pin 7 unconnected (NC). Therefore, THS4131CD operates continuously whenever powered and cannot be placed into low-quiescent-current shutdown mode. Designers requiring power gating must use THS4130CD or implement external supply switching.

What supply voltage ranges does THS4131CD support?

THS4131CD supports dual supplies from ±2.5 V to ±15 V or single supplies from 5 V to 30 V. At ±15 V, it delivers full 170 MHz bandwidth and ±11.2 V output swing into 1 kΩ. Operation at ±2.5 V reduces bandwidth to 165 MHz but maintains –101 dBc THD at 250 kHz - enabling flexible deployment across battery-powered and high-voltage industrial systems.

How does VOCM affect THS4131CD output behavior?

VOCM sets the DC common-mode voltage of both THS4131CD outputs. When driven by a low-impedance source (e.g., DAC or voltage reference), VOCM directly establishes the midpoint between VOUT+ and VOUT−. If left floating, VOCM defaults to (VCC+ + VCC−)/2. A 0.1 µF bypass capacitor is mandatory to suppress noise coupling onto this sensitive node, as VOCM errors directly translate to output common-mode imbalance.

Can THS4131CD drive capacitive loads directly?

No - THS4131CD requires a series resistor (≥20 Ω) between each output and capacitive loads exceeding 10 pF to maintain stability. Without this isolation, internal compensation interacts with load capacitance causing high-frequency ringing or oscillation. For 50 Ω transmission lines, a 50 Ω series resistor provides both isolation and source termination; PCB layout must minimize stub length after the resistor.

What resistor tolerance is required for optimal THS4131CD performance?

THS4131CD requires ≤1% tolerance for all external feedback and gain-setting resistors (RG and RF) to maintain output balance error below 0.1%, preserve CMRR >80 dB, and prevent degradation of PSRR and second-harmonic distortion. Table 9-1 in the datasheet specifies exact values: e.g., 390 Ω for unity gain, 750 Ω for G = 2. Using 5% resistors increases output common-mode error and measurable THD by >10 dB.