Texas Instruments THS4131CDR

Overview

THS4131CDR from Texas Instruments is a fully differential amplifier (FDA) designed for high-speed, low-noise signal conditioning in precision analog front-ends. It delivers 170 MHz small-signal bandwidth, 51 V/µs slew rate, and –102 dBc THD at 250 kHz with ±15 V supplies, enabling high-fidelity differential ADC driving and single-ended-to-differential conversion in medical ultrasound and test equipment.

For engineers reviewing the THS4131CDR datasheet, THS4131CDR pinout, THS4131CDR application, or THS4131CDR equivalent, this page provides verified specifications, SOIC-8 package details, functional mode distinctions versus THS4130, VOCM-controlled output common-mode setting, and real-world design implications of its 1.25 nV/√Hz input voltage noise and 95 dB CMRR at 800 kHz.

Technical Context

The THS4131CDR implements a true fully differential signal path from input to output using TI's high-voltage complementary bipolar process, supporting supply ranges from ±2.5 V to ±15 V (or 5–30 V single-supply). Its architecture includes matched internal 10-kΩ resistors tied to the VOCM error amplifier, enabling precise common-mode output control independent of gain configuration.

Unlike the THS4130, the THS4131CDR lacks a power-down (PD) pin - Pin 7 is NC - eliminating shutdown functionality but simplifying biasing and reducing external component count. Its differential output impedance is determined by both feedback network topology and internal resistive elements, with typical >1 MΩ output impedance in high-impedance states when improperly terminated.

Key Specifications

Pinout & Package

THS4131CDR is packaged in an 8-pin SOIC (D package), with lead finish NiPdAu, RoHS-compliant, and moisture sensitivity level (MSL) 2a per JEDEC J-STD-020. Thermal resistance R_θJA = 126.3°C/W enables operation up to +85°C ambient with standard PCB copper area.

Key Features

Applications

Equivalent & Alternatives

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

Compared with THS4131CDR, THS4131IDR offers identical performance with extended temperature capability, while THS4561IRGET trades higher power and different packaging for significantly greater bandwidth and lower noise - making it suitable for next-generation wideband receivers but over-specified for standard 100-MHz-class data acquisition.

Availability

THS4131CDR is available at Aetrix Electronics and suitable for medical ultrasound front-ends, high-speed data acquisition systems, and industrial test instrumentation requiring stable component supply across long production lifecycles.

Supply support for THS4131CDR 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 precision signal chain solutions.

The THS413x family was engineered specifically for demanding differential signal conditioning tasks - including ADC driving, ultrasound beamforming, and high-fidelity instrumentation - where low noise, high bandwidth, and robust common-mode rejection are essential.

FAQ

What is the key functional difference between THS4131CDR and THS4130CDR?

The THS4131CDR has no power-down (PD) pin - Pin 7 is NC - whereas THS4130CDR uses Pin 7 as an active-low shutdown control. This means THS4131CDR operates continuously and cannot enter low-quiescent-current mode. All other electrical characteristics, pinout, and package dimensions are identical between the two for the SOIC-8 variant. THS4131CDR is therefore preferred in always-on signal chains where simplicity and reliability outweigh power savings.

Does THS4131CDR support single-supply operation, and what is the minimum recommended supply voltage?

Yes, THS4131CDR supports true single-supply operation from 5 V to 30 V. The minimum recommended supply is 5 V (i.e., VCC+ = 5 V, VCC− = 0 V), which maintains specified AC performance including ≥165 MHz bandwidth and –101 dBc THD at 250 kHz. At 5 V, output swing is 1.2 V to 3.8 V (RL = 1 kΩ), making it compatible with 3.3-V or 5-V ADC references when VOCM is set appropriately.

How does the VOCM pin affect THS4131CDR output behavior, and what happens if it is left unconnected?

The VOCM pin sets the average DC voltage of VOUT+ and VOUT−. If left unconnected, an internal divider defaults VOCM to (VCC+ + VCC−)/2 - mid-rail - establishing symmetric output swing. However, leaving VOCM floating risks noise coupling; TI recommends bypassing it with a 0.1-µF capacitor to ground. Applying an external voltage (e.g., 1.25 V) shifts the entire differential output window, enabling direct interface to ADCs with non-mid-rail input ranges.

What is the maximum capacitive load THS4131CDR can drive without external isolation, and how should heavier loads be handled?

THS4131CDR is stable driving ≤10 pF directly. For loads >10 pF (e.g., ADC input capacitance + PCB trace), TI specifies adding a 20 Ω series resistor at each output (VOUT+ and VOUT−) to isolate capacitance and restore phase margin. This resistor also provides source termination in 50-Ω systems. Without it, ringing or oscillation occurs above ~10 MHz, degrading settling time and harmonic distortion performance.

Is THS4131CDR pin-compatible with other members of the THS413x family, and can it replace THS4130CDR on the same PCB?

THS4131CDR is pin-compatible with THS4130CDR in the SOIC-8 (D) package - all signal pins (VIN+, VIN−, VOCM, VOUT+, VOUT−, VCC+, VCC−) occupy identical positions. However, Pin 7 is NC on THS4131CDR but PD on THS4130CDR. To substitute, leave Pin 7 unconnected or tie it to VCC+ (not VCC−); do not assert PD logic. No layout change is required, but power-down functionality is forfeited.