Texas Instruments THS4120IDGN

Overview

THS4120IDGN from Texas Instruments is a high-speed, fully differential-input/differential-output amplifier optimized for single-supply ADC driver applications. It delivers 100 MHz –3 dB bandwidth, 55 V/µs slew rate, –75 dB THD at 1 MHz (2 VPP), 5.4 nV/√Hz input noise, and features an integrated power-down pin (PD) enabling quiescent current reduction from 11 mA to 120 µA. It operates from a 3.3 V single supply and supports differential antialiasing filtering in precision data acquisition systems.

For engineers reviewing the THS4120IDGN datasheet, THS4120IDGN pinout, THS4120IDGN application, or THS4120IDGN equivalent, key selection considerations include its power-down functionality, VOCM-controlled output common-mode level, MSOP PowerPAD™ thermal performance, and compatibility with 800 Ω load-driven 2 VPP differential outputs into high-resolution ADCs.

Technical Context

The THS4120IDGN implements a true fully differential signal path-both inputs and outputs are balanced differential pairs-enabling inherent common-mode noise rejection, second-harmonic cancellation, and improved PSRR (85 dB typ). Its internal architecture supports precise VOCM control of output DC level, allowing seamless interfacing with ADC reference voltages without transformers.

Unlike conventional op-amps, it uses symmetrical gain-setting resistor networks (Rf/Rg) to maintain balance; mismatch >1% degrades CMRR and distortion performance. The PD pin requires an external 10-kΩ pullup to VDD for reliable enable/disable control, with defined threshold voltages (Enable >1.4 V, Disable <1.2 V) referenced to supply rails.

Key Specifications

Pinout & Package

The THS4120IDGN is housed in an 8-pin MSOP PowerPAD™ package (DGN), featuring an exposed thermal pad on the underside for enhanced heat dissipation. The PowerPAD must be soldered to a thermally conductive PCB copper area to maintain junction temperature ≤125°C under continuous operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with THS4120IDGN, THS4121IDGN removes power-down capability but retains identical AC performance, while THS4131IDGN trades single-supply simplicity for wider bandwidth and lower noise at the cost of supply complexity and higher power.

Availability

THS4120IDGN is available at Aetrix Electronics and suitable for high-speed data acquisition, industrial sensor interface, and communications baseband processing requiring stable component supply across extended temperature ranges (–40°C to +85°C).

Supply support for THS4120IDGN 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-speed amplifier design and manufacturing.

The THS412x family was engineered specifically for precision, single-supply, fully differential signal conditioning-targeting ADC driver, antialiasing, and differential transmission roles in test & measurement, medical, and industrial systems.

FAQ

What is the function of the PD pin on the THS4120IDGN?

The PD (Power-Down) pin on the THS4120IDGN is an active-high enable control that reduces quiescent current from 11 mA to 120 µA when driven low. It requires a 10-kΩ pullup resistor to VDD for reliable operation. The THS4120IDGN enters low-power mode when PD voltage falls below 1.2 V, and resumes full operation within 4.8 µs after PD rises above 1.4 V. This feature is unique to the THS4120IDGN within the THS412x family.

Can the THS4120IDGN operate from a 3.3 V single supply without performance degradation?

Yes-the THS4120IDGN is explicitly characterized and optimized for 3.3 V single-supply operation. All key specifications-including 100 MHz bandwidth, –75 dB THD at 1 MHz, and 55 V/µs slew rate-are guaranteed at VDD = 3.3 V. Its common-mode input range (0.35 V to VDD – 0.1 V) and VOCM-controlled output level ensure full rail-to-rail usability without clipping or distortion penalties.

How does the VOCM pin affect THS4120IDGN output behavior?

The VOCM pin sets the DC common-mode voltage of both differential outputs (VOUT+ and VOUT−). When left unconnected, VOCM defaults to VDD/2 (1.65 V at 3.3 V supply), centering the differential output swing. For optimal ADC interfacing, connect VOCM directly to the ADC's reference voltage (VREF) using a 0.1 µF bypass capacitor. This ensures precise output level alignment and eliminates DC offset errors in the THS4120IDGN signal chain.

Is the THS4120IDGN pin-compatible with other devices in the THS412x family?

Yes-the THS4120IDGN shares identical 8-pin MSOP (DGN) pinout with THS4121IDGN, differing only in Pin 6: THS4120IDGN uses PD (power-down), while THS4121IDGN uses NC (no connect). All other pins (VIN−, VOCM, VDD, VOUT+, VIN+, GND, VOUT−) are functionally and physically identical. This allows drop-in replacement where power-down is not required, provided the PD pin is tied high or left floating with appropriate pullup.

What thermal considerations apply to the THS4120IDGN's PowerPAD™ package?

The THS4120IDGN's DGN package includes an exposed thermal pad that must be soldered to a dedicated PCB copper pour for effective heat dissipation. TI specifies θJA = 58.4 °C/W and maximum continuous junction temperature of 125°C. To avoid thermal derating, the THS4120IDGN's thermal pad requires ≥4 thermal vias (0.3 mm diameter) connecting to an inner ground plane, and the surrounding copper area should exceed 100 mm². Failure to implement this compromises long-term reliability and distortion performance.