Texas Instruments THS4021CD

Overview

THS4021CD from Texas Instruments is a single-channel, ultra-low-noise, voltage-feedback operational amplifier optimized for high-fidelity signal conditioning in precision high-speed applications. It delivers 1.2nV/√Hz input voltage noise, 290MHz small-signal bandwidth at G=10, 470V/μs slew rate, and 30ns 0.1% settling time - enabling accurate amplification of fast, low-amplitude signals in ultrasound front-ends and source measurement units.

For engineers reviewing the THS4021CD datasheet, THS4021CD pinout, THS4021CD application, or THS4021CD equivalent, key selection criteria include its stable operation at ≥10V/V gain, ±4.5V to ±16V dual-supply flexibility, offset nulling capability, and 200mA output drive - critical for driving reactive loads in medical imaging and power quality instrumentation.

Technical Context

The THS4021CD employs a voltage-feedback architecture with fully differential input stage and high-current Class-AB output stage, supporting stable closed-loop operation at gains ≥10V/V without external compensation. Its 2GHz gain-bandwidth product enables wideband signal processing while maintaining low distortion (–68dBc THD at 1MHz, RL=150Ω).

Designed for dual-supply operation, it features rail-to-rail input common-mode range (±14.3V at ±15V supplies) and robust output swing (±12.9V into 250Ω), with dedicated NULL pins enabling precise DC offset trimming - essential for DC-coupled high-gain chains in SMU and oscilloscope front-ends.

Key Specifications

Pinout & Package

THS4021CD is available in 8-pin SOIC (D package), with thermal resistance RθJA = 124.5°C/W and footprint compatible with industry-standard PCB layouts for high-speed op-amps.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed, low-noise op-amp applications.

Compared with OPA656U and LMH6629MA, THS4021CD uniquely balances ultra-low noise, gain stability at ≥10V/V, offset adjust capability, and wide ±4.5V to ±16V supply support - making it the only option among the three suitable for DC-coupled, high-voltage, precision high-speed instrumentation.

Availability

THS4021CD is available at Aetrix Electronics and suitable for ultrasound scanner front-ends, source measurement units, and power quality meters requiring stable component supply, long-term manufacturability, and consistent electrical performance across production lots.

Supply support for THS4021CD 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 op-amps and precision signal-chain solutions.

The THS402x family was engineered specifically for demanding high-speed, low-noise applications including medical imaging, automated test equipment, and precision instrumentation - where signal fidelity, DC accuracy, and robust output drive are simultaneously critical.

FAQ

What is the minimum stable gain for THS4021CD?

The THS4021CD is unconditionally stable at closed-loop gains of 10V/V and greater, as well as at inverting gains of –9V/V or less. This eliminates the need for external compensation networks in standard non-inverting or inverting amplifier configurations operating within these gain ranges, simplifying design and improving phase margin predictability across temperature and process variation.

Does THS4021CD support single-supply operation?

Yes, THS4021CD supports single-supply operation from 9V to 32V. When used in single-supply mode, the input common-mode range extends from 0.2V above V– to 0.2V below V+, and output swing remains rail-to-rail within specified load conditions. Designers must ensure proper biasing of the input common-mode voltage and use appropriate level-shifting techniques for AC-coupled signal paths.

How do I use the NULL pins on THS4021CD?

To use the NULL pins on THS4021CD, connect a 10kΩ potentiometer between Pins 1 and 8, with its wiper tied to VCC– (Pin 4). Adjusting the potentiometer minimizes input offset voltage - typically reducing VOS from ±2mV to <100μV. This procedure is performed once during calibration and is especially valuable in DC-coupled, high-gain applications such as SMU current-sense amplifiers where residual offset directly impacts measurement accuracy.

What is the maximum output current capability of THS4021CD?

The THS4021CD delivers up to 200mA of continuous output current per amplifier under typical conditions (±15V supplies, TA = 25°C), with short-circuit current limited to 240mA. Sustained high-current operation requires attention to thermal management: junction temperature must remain below 150°C, and PCB copper area should be maximized beneath the D-package SOIC to dissipate heat effectively given its 124.5°C/W junction-to-ambient thermal resistance.

Can THS4021CD drive a 50Ω load?

Yes, THS4021CD can drive a 50Ω load, delivering ±12V output swing at ±15V supplies with acceptable distortion (–55dBc THD at 1MHz, 50Ω). However, full 200mA output current is not sustainable into 50Ω without significant voltage droop or thermal stress. For continuous 50Ω driving, limit peak output to ≤±10V and ensure adequate heatsinking or derate supply current per TI's thermal guidelines in Section 5.4 of the datasheet.