Texas Instruments THS4120CDGNR

Overview

THS4120CDGNR from Texas Instruments is a high-speed, fully differential-input/differential-output amplifier optimized for single-supply ADC driving at 3.3 V. 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 - used in precision data acquisition systems interfacing with 12–16-bit SAR or sigma-delta ADCs.

For engineers reviewing the THS4120CDGNR datasheet, THS4120CDGNR pinout, THS4120CDGNR application, or THS4120CDGNR equivalent, key selection criteria include differential output drive capability into 800 Ω loads, VOCM-controlled common-mode level shifting, PD pin logic thresholds (enable >1.4 V, disable <1.2 V), and PowerPAD™ thermal management requirements for sustained 125°C junction operation.

Technical Context

The THS4120CDGNR implements a true fully differential signal path with matched internal transconductance stages, enabling balanced output swing and second-harmonic cancellation. Its architecture supports both differential-input/differential-output and single-ended-input/differential-output configurations without external level-shifting components.

It operates from a single 3.3 V supply (3.0–3.5 V range), with VOCM pin setting output common-mode voltage (typically VDD/2 = 1.65 V) and PD pin controlling enable/disable via resistor-pullup (10 kΩ to VDD). The device uses TI's submicron CMOS process and requires external 0.1 µF bypass on VOCM for noise suppression.

Key Specifications

Pinout & Package

THS4120CDGNR is housed in an 8-pin MSOP PowerPAD™ package (DGN), featuring an exposed thermal pad on the underside that must be soldered to a PCB copper pour for thermal conduction. The package supports JEDEC-standard reflow and requires θJA = 58.4°C/W thermal design for 125°C junction limit at TA = 85°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with THS4120CDGNR, THS4131CDGNR offers higher bandwidth but lacks native 3.3 V optimization and power-down, while THS4561IRGET provides superior noise performance and output swing but sacrifices low-power standby capability and compact DGN packaging.

Availability

THS4120CDGNR is available at Aetrix Electronics and suitable for precision data acquisition, industrial IO-Link transceivers, and medical sensor signal conditioning requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for THS4120CDGNR 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 amplifiers and precision signal chain solutions.

The THS4120CDGNR belongs to TI's THS412x family of fully differential I/O amplifiers, designed specifically for single-supply ADC driver applications demanding low distortion, wide bandwidth, and power-efficient operation in space-constrained industrial and medical systems.

FAQ

What is the function of the PD pin on the THS4120CDGNR?

The PD (Power-Down) pin on the THS4120CDGNR is an active-high enable control that reduces quiescent current from 11 mA to 120 µA when driven low. For normal operation, it must be pulled high to VDD via a 10 kΩ resistor. The THS4120CDGNR enters power-down mode when PD voltage falls below 1.2 V and resumes full operation when PD exceeds 1.4 V, with 4.8 µs turn-on delay.

Can the THS4120CDGNR operate from a 3.3 V supply only?

Yes, the THS4120CDGNR is specified for single-supply operation at 3.3 V (range: 3.0 V to 3.5 V). Its electrical characteristics - including 100 MHz bandwidth, –75 dB THD, and 55 V/µs slew rate - are guaranteed under these conditions. It does not support dual-supply operation or voltages outside this range without derating or functional risk.

How should the VOCM pin be configured for optimal THS4120CDGNR performance?

The VOCM pin on the THS4120CDGNR sets the common-mode voltage of both differential outputs. For standard 3.3 V operation, it defaults to VDD/2 = 1.65 V. To ensure stability and noise immunity, connect a 0.1 µF ceramic capacitor directly from VOCM to ground. If interfacing with an ADC's VREF output, route VREF → 0.1 µF → VOCM to maintain precise level alignment.

Does the THS4120CDGNR require external compensation for capacitive loads?

Yes - the THS4120CDGNR is internally compensated for maximum bandwidth and slew rate, making it sensitive to capacitive loading. For loads >10 pF, place a 20 Ω series resistor between each output (VOUT+, VOUT−) and the load. This isolates capacitance, restores phase margin, and prevents high-frequency ringing - especially critical in PCB traces longer than 2 cm or when driving ADC input capacitance.

What thermal design considerations apply to the THS4120CDGNR's PowerPAD™ package?

The THS4120CDGNR'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; to maintain TJ ≤ 125°C at TA = 85°C, the pad must connect to ≥250 mm² of 2-oz copper with ≥4 thermal vias (0.3 mm diameter) to inner ground planes. Failure to implement this risks permanent damage above 125°C junction temperature.