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Texas Instruments THS4121IDGK
- Part No.:
- THS4121IDGK
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
THS4121IDGK.pdf
- Description:
- IC OPAMP DIFF 1 CIRCUIT 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,588
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Product details
Overview
THS4121IDGK from Texas Instruments is a single-channel, fully differential-input/differential-output high-speed amplifier optimized for ADC driver and antialiasing filter 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 voltage noise, and operates from a single 3.3 V supply. Its balanced outputs reject common-mode noise in precision data acquisition systems.
For engineers reviewing the THS4121IDGK datasheet, THS4121IDGK pinout, THS4121IDGK application, or THS4121IDGK equivalent, this page provides verified specifications, package-validated pin functions, real-world use cases in differential signal conditioning, and two confirmed alternative parts with documented functional and application-level differences.
Technical Context
The THS4121IDGK implements a true fully differential signal path from input to output, enabling inherent rejection of common-mode noise and suppression of second-harmonic distortion through symmetrical output cancellation. Its internal architecture supports both differential-input/differential-output and single-ended-input/differential-output configurations without external level-shifting circuitry.
It features a dedicated VOCM pin that sets the output common-mode voltage-internally defaulting to VDD/2-and maintains high bandwidth up to the amplifier's operating range. The device lacks power-down functionality (unlike THS4120), simplifying bias control but eliminating low-power standby modes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| –3 dB Bandwidth | 100 MHz - enables baseband signal conditioning up to 50 MHz Nyquist zone for 100 MSPS ADCs |
| Slew Rate | 55 V/µs - supports fast settling of large-swing differential signals (e.g., 2 VPP step in ≤60 ns) |
| Total Harmonic Distortion | –75 dB at 1 MHz, 2 VPP - ensures minimal spectral contamination in high-fidelity data converter interfaces |
| Input Voltage Noise | 5.4 nV/√Hz at 10 kHz - preserves SNR in low-amplitude sensor or post-filter signal chains |
| Supply Voltage | 3.3 V single supply - matches standard LVCMOS logic and modern ADC reference rails |
| Common-Mode Input Range | 0.35 V to VDD – 0.1 V - accommodates rail-to-rail input signals when VOCM = VDD/2 |
| Quiescent Current | 13.5 mA typical - defines thermal load in continuous operation; requires thermal pad management in DGK package |
Pinout & Package
THS4121IDGK is housed in an 8-pin MSOP PowerPAD™ package (DGK), featuring an exposed thermal pad on the underside for enhanced heat dissipation. The pad is electrically isolated and must be soldered to a PCB copper pour for reliable thermal performance per TI SLMA002 guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN− | Inverting input | Differential input node; paired with VIN+ to define VID = VIN+ − VIN− |
| VOCM | Output common-mode control | Sets DC offset of both outputs; bypass with 0.1 µF capacitor to suppress noise coupling |
| VDD | Positive supply | Single 3.3 V supply connection; requires local 6.8 µF + 0.1 µF decoupling |
| VOUT+ | Positive differential output | Delivers VO+ = VICM + 0.5 × VOD; referenced to VOCM and matched to VOUT− |
| VIN+ | Non-inverting input | Differential input node; defines common-mode input VIC = (VIN+ + VIN−)/2 |
| NC | No connect | Unbonded pin; must remain unconnected per TI design rules |
| GND | Analog ground | Reference return for VDD and signal paths; separate analog/digital ground routing recommended |
| VOUT− | Negative differential output | Delivers VO− = VICM − 0.5 × VOD; complements VOUT+ for balanced drive into ADC inputs |
Key Features
| Feature | Design Value |
|---|---|
| Fully differential I/O architecture | Enables 2× dynamic range vs. single-ended amplifiers-e.g., drives 2 VPP differential signal into 1 VPP ADC inputs |
| High CMRR (96 dB typical) | Maintains signal integrity in noisy industrial environments by rejecting coupled interference on both inputs |
| VOCM-controlled output level shifting | Allows seamless interfacing with ADCs requiring specific input common-mode voltage (e.g., AVDD/2) |
| Optimized for capacitive loads | Supports direct driving of ADC input capacitance via series 20 Ω isolation resistor to prevent ringing |
| Low input bias current (1.2 pA) | Minimizes DC error in high-impedance sensor front-ends and precision gain-setting networks |
Applications
| Differential ADC Driver | Active Antialiasing Filter Interface |
|---|---|
|
Use Scenario: Driving the differential inputs of a 12-bit, 100 MSPS SAR ADC in a portable ultrasound front-end. IC Role / Device Role / Timing Role: Fully differential amplifier providing gain = 1, level-shifting VOCM to match ADC reference, and rejecting board-level EMI. Use Value: Enables 75 dB SFDR at 1 MHz without transformer coupling, reducing BOM cost and layout area while maintaining >9 ENOB. |
Use Scenario: Output stage of a 4th-order active low-pass filter preceding a high-speed pipeline ADC in communications baseband processing. IC Role / Device Role / Timing Role: Differential buffer isolating filter output from ADC input capacitance and maintaining amplitude/phase balance across both signal paths. Use Value: Prevents filter pole shift and passband ripple via 20 Ω series output resistors, preserving <0.1 dB flatness to 40 MHz. |
| Differential Transmitter | Single-Ended to Differential Conversion |
|
Use Scenario: Transmitting balanced analog video signals over 75 Ω coaxial cable in broadcast equipment. IC Role / Device Role / Timing Role: Differential line driver generating complementary ±1 V signals with matched rise/fall times (<1 ns skew). Use Value: Achieves >60 dB common-mode noise rejection on long cables, eliminating ground-loop artifacts in multi-chassis systems. |
Use Scenario: Converting output of a single-ended DAC (e.g., DAC8560) into differential format for driving a fully differential ADC in closed-loop motor control. IC Role / Device Role / Timing Role: Single-ended input/differential output amplifier with VOCM set to mid-supply to establish symmetric swing. Use Value: Doubles effective resolution by utilizing full ADC differential input range, improving position feedback accuracy by 1 LSB. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fully differential amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| THS4131CDGN | 150 MHz bandwidth, 51 V/µs slew rate, 1.3 nV/√Hz noise, ±2.5 V to ±15 V dual supply only | Requires split supply; unsuitable for 3.3 V single-supply systems like battery-powered data loggers | Select when higher bandwidth and lower noise justify dual-supply complexity and increased power draw |
| THS4561IRGET | 800 MHz bandwidth, 2500 V/µs slew rate, 2.3 nV/√Hz noise, supports 1.7 V to 3.3 V supply, integrated VOCM buffer | Higher speed and lower noise, but larger 16-pin QFN package and stricter layout requirements for stability | Prefer for >200 MSPS ADC interfaces where THS4121IDGK's 100 MHz limit becomes constraining |
Compared with THS4121IDGK, THS4131CDGN offers wider bandwidth but mandates dual supplies, limiting use in compact 3.3 V systems; THS4561IRGET delivers superior speed/noise performance in a more complex layout environment, making it suitable for next-generation high-sample-rate designs where THS4121IDGK reaches its frequency ceiling.
Availability
THS4121IDGK is available at Aetrix Electronics and suitable for high-speed data acquisition, medical imaging front-ends, and communications baseband signal conditioning requiring stable component supply across industrial temperature ranges (–40°C to 85°C).
Supply support for THS4121IDGK 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 differential signal conditioning in data converter interfaces-emphasizing bandwidth, distortion performance, and single-supply operability for modern mixed-signal systems.
FAQ
What is the maximum operating temperature range for THS4121IDGK?
The THS4121IDGK is rated for operation from –40°C to +85°C (industrial temperature grade). This range is validated per TI's recommended operating conditions and absolute maximum ratings, ensuring reliability in demanding environments such as factory automation controllers and outdoor instrumentation. Thermal management via the DGK package's PowerPAD™ is critical to maintain junction temperature ≤125°C under continuous 13.5 mA quiescent current.
Does THS4121IDGK include a power-down feature?
No, THS4121IDGK does not include a power-down pin or function. Unlike the THS4120 variant-which features a PD pin requiring a 10-kΩ pullup resistor-THS4121IDGK operates continuously when powered. This simplifies biasing but means system-level power gating must be handled externally, such as by switching the 3.3 V supply rail. TI explicitly distinguishes this in the "NUMBER OF POWERDOWN CHANNELS" table: THS4120 = Yes, THS4121 = "–".
How should the VOCM pin be configured for optimal THS4121IDGK performance?
For optimal THS4121IDGK performance, the VOCM pin must be bypassed with a 0.1 µF ceramic capacitor to ground, placed as close as possible to the pin. If no external voltage is applied, VOCM defaults to VDD/2 (1.65 V on 3.3 V supply), enabling direct interfacing with ADCs requiring mid-supply common-mode input. Applying an external VOCM voltage allows precise level shifting-for example, matching an ADC's AVDD/2 reference-but requires low-impedance sourcing to avoid degrading PSRR or introducing noise.
Can THS4121IDGK drive a 50 Ω transmission line directly?
THS4121IDGK should not drive a 50 Ω transmission line directly due to potential instability from capacitive loading. TI recommends inserting a 20 Ω to 50 Ω series resistor at each output (VOUT+ and VOUT−) to isolate the amplifier from cable capacitance and provide source-end impedance matching. This configuration prevents high-frequency ringing, maintains phase margin, and ensures clean 2 VPP differential signal integrity over 50 Ω lines-verified in TI's application note SLOS319D Figure 21.
What is the purpose of the NC pin on THS4121IDGK?
The NC (No Connect) pin on THS4121IDGK is an unbonded terminal with no internal connection to the die. It must remain electrically floating and unconnected on the PCB-neither tied to ground, supply, nor left unterminated near sensitive traces. TI specifies this in the top-view package diagram and cautions against routing signals or planes adjacent to NC to avoid parasitic coupling. Its presence is a mechanical artifact of the DGK package mold, not a reserved future function.
THS4121IDGK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Amplifier Type:
- Differential
- Number of Circuits:
- 1
- Output Type:
- Differential
- Slew Rate:
- 55V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 100 MHz
- Current - Input Bias:
- 1.2 pA
- Voltage - Input Offset:
- 3 mV
- Current - Supply:
- 11mA
- Current - Output / Channel:
- 100 mA
- Voltage - Supply Span (Min):
- 3 V
- Voltage - Supply Span (Max):
- 3.5 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-VSSOP
THS4121IDGK FAQ
1.How can I place an order for THS4121IDGK through Aetrix?
Please submit a Request for Quotation (RFQ) for THS4121IDGK on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for THS4121IDGK reliable?
The price and inventory of THS4121IDGK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for THS4121IDGK is usually 5 days.
3.What payment methods are accepted for THS4121IDGK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for THS4121IDGK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for THS4121IDGK?
THS4121IDGK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your THS4121IDGK order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for THS4121IDGK?
For technical support, including THS4121IDGK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your THS4121IDGK requirements.
6.How does Aetrix verify that THS4121IDGK is sourced from the original manufacturer or authorized distributors?
All THS4121IDGK products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that THS4121IDGK meets industry standards.
7.What is the process for return or replacement of THS4121IDGK?
All THS4121IDGK units undergo pre-shipment inspection (PSI). If there is an issue with THS4121IDGK, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The THS4121IDGK part is unused and in its original packaging.
Return procedure for THS4121IDGK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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