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Texas Instruments THS4121ID
- Part No.:
- THS4121ID
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
THS4121ID.pdf
- Description:
- IC OPAMP DIFF 1 CIRCUIT 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,755
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Product details
Overview
THS4121ID from Texas Instruments is a single-channel, fully differential-input/differential-output high-speed amplifier optimized for ADC driving and antialiasing in 3.3-V single-supply systems. It delivers 100 MHz bandwidth, 55 V/µs slew rate, –75 dB THD at 1 MHz (2 VPP), 5.4 nV/√Hz input noise, and operates across –40°C to 85°C industrial temperature range.
For engineers reviewing the THS4121ID datasheet, THS4121ID pinout, THS4121ID application, or THS4121ID equivalent, this page provides verified specifications, package mapping to MSOP PowerPAD™ (DGN) and SOIC (D), validated differential ADC driver use cases, and two confirmed alternative parts with documented functional and application differences.
Technical Context
The THS4121ID implements a true fully differential signal path from input to output, enabling balanced common-mode noise rejection and second-harmonic cancellation. Its VOCM pin sets output common-mode level independently, supporting midrail biasing (VDD/2) without external resistors and enabling direct interface to ADC reference outputs.
Internally compensated for maximum bandwidth and slew rate, it requires series output resistance (≥20 Ω) when driving >10 pF capacitive loads to maintain phase margin. It lacks power-down functionality-unlike the THS4120ID-making it suitable for always-on high-fidelity signal chains where quiescent current stability is critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| –3 dB Bandwidth | 100 MHz - supports wideband baseband and IF signal conditioning up to Nyquist of 50-MSPS ADCs |
| Slew Rate | 55 V/µs - enables clean 2-VPP differential step response with 60-ns 0.1% settling time |
| Total Harmonic Distortion | –75 dB at 1 MHz, 2 VPP - meets SFDR requirements for 12-bit+ precision data acquisition |
| Input Voltage Noise | 5.4 nV/√Hz at 10 kHz - preserves SNR in low-level sensor and audio front-end amplification |
| Supply Voltage Range | 3.0 V to 3.5 V single supply - compatible with standard 3.3-V logic and ADC reference rails |
| Operating Temperature | –40°C to +85°C - qualified for industrial and automotive under-hood signal conditioning |
| Quiescent Current | 13.5 mA typical - fixed bias enables predictable thermal design without mode-switching transients |
Pinout & Package
THS4121ID is available in SOIC (D, 8-pin) and thermally enhanced MSOP PowerPAD™ (DGN, 8-pin) packages. The DGN variant includes an exposed thermal pad electrically isolated from all terminals, requiring solder connection to PCB copper for optimal junction-to-board thermal resistance (θJC = 4.7°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN− | Inverting input | Differential input node; matched impedance critical for CMRR & harmonic cancellation |
| VOCM | Output common-mode control | DC bias setting point for both outputs; bypass with 0.1-µF capacitor for noise immunity |
| VDD | Positive supply | Single 3.3-V rail; requires local 6.8-µF + 0.1-µF decoupling per layout guidelines |
| VOUT+ | Positive differential output | Delivers inverted complement of VIN+ relative to VOCM; drives one ADC input |
| VIN+ | Non-inverting input | Differential input node; symmetric trace routing required to preserve balance |
| NC | No connect | Pin 6 is unconnected internally; must remain floating or grounded per PCB design rules |
| GND | Analog ground reference | Low-inductance return path; separate analog/digital ground planes recommended |
| VOUT− | Negative differential output | Delivers non-inverted complement of VIN− relative to VOCM; drives opposite ADC input |
Key Features
| Feature | Design Value |
|---|---|
| Fully differential I/O architecture | Enables 2× dynamic range vs. single-ended amps: delivers 2-VPP differential swing into 1-VPP ADC inputs |
| Balanced output common-mode rejection | 96 dB CMRR over DC–100 kHz ensures robust immunity to coupled noise on PCB traces and supplies |
| Single-supply operation with internal midrail VOCM | Eliminates need for external resistor dividers; simplifies interface to 3.3-V ADCs with VREF output |
| Optimized for antialias filtering | Stable with R-C filter networks directly at output; supports active low-pass configurations without peaking |
| Thermally enhanced PowerPAD™ packaging (DGN) | Reduces θJA to 58.4°C/W - enables 1.71 W power dissipation at 25°C ambient for sustained high-speed operation |
Applications
| High-Speed Data Acquisition | Differential Communication Transceivers |
|---|---|
|
Use Scenario: Driving the differential input of a 12-bit, 50-MSPS pipeline ADC in a medical ultrasound front-end. IC Role / Device Role / Timing Role: ADC driver with precise gain = 1, VOCM referenced to ADC's internal 1.65-V VREF, providing matched 2-VPP complementary signals. Use Value: –75 dB THD ensures <0.002% distortion at 1 MHz, preserving image resolution and Doppler accuracy without post-processing correction. |
Use Scenario: Transmitting balanced analog video over coaxial cable in broadcast equipment with EMI-sensitive environments. IC Role / Device Role / Timing Role: Differential transmitter stage converting single-ended CVBS or SDI clock signals to low-noise, common-mode-rejected outputs. Use Value: 100 MHz bandwidth supports full NTSC/PAL luminance bandwidth; 5.4 nV/√Hz noise floor maintains >65 dB SNR over 50-m cable runs. |
| Industrial Sensor Signal Conditioning | Test & Measurement Instrumentation |
|
Use Scenario: Amplifying low-level bridge sensor outputs (e.g., load cell, pressure transducer) before digitization in PLC analog input modules. IC Role / Device Role / Timing Role: Precision differential gain stage with VOCM set to mid-supply, rejecting power supply ripple and EMI-induced common-mode interference. Use Value: 96 dB CMRR and 64 dB minimum over full temperature range suppresses 50/60-Hz line noise and switching regulator artifacts in noisy factory floors. |
Use Scenario: Output stage of a 100-MHz arbitrary waveform generator delivering calibrated differential test signals to oscilloscope inputs. IC Role / Device Role / Timing Role: High-fidelity buffer ensuring flat frequency response and minimal group delay variation from DC to 100 MHz. Use Value: 55 V/µs slew rate and 60-ns 0.1% settling enable accurate reproduction of fast-edged pulses and multi-tone RF waveforms. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fully differential amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| THS4131ID | 150 MHz BW, 51 V/µs SR, 1.3 nV/√Hz noise, ±2.5 V to ±15 V dual-supply only | Requires split supply; superior noise performance but incompatible with 3.3-V single-rail systems | Select when dual-supply headroom allows and ultra-low noise (<1.5 nV/√Hz) is mandatory for >14-bit resolution |
| THS4561IRGET | 1.8-GHz GBW, 3000 V/µs SR, 2.2 nV/√Hz, supports 2.7–5.5 V single supply, integrated VOCM buffer | Higher bandwidth and speed; VOCM buffer eliminates external op-amp for reference buffering | Select for >200-MSPS ADC drivers or when VOCM source impedance >1 kΩ would degrade THS4121ID performance |
Compared with THS4121ID, THS4131ID offers higher bandwidth and lower noise but mandates dual supplies, while THS4561IRGET delivers GHz-class speed and integrated VOCM drive at the cost of increased quiescent current (22 mA) and complexity in layout-sensitive RF designs.
Availability
THS4121ID is available at Aetrix Electronics and suitable for high-speed data acquisition, industrial sensor interfaces, and test instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for THS4121ID 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, embedded processing, and high-performance signal chain solutions, with decades of expertise in precision amplifiers and data converter interfaces.
The THS412x family was designed specifically for high-fidelity differential signal conditioning in single-supply data acquisition systems, emphasizing distortion-free ADC driving, robust common-mode rejection, and thermal reliability in compact packages.
FAQ
What is the function of the NC pin on the THS4121ID?
Pin 6 of the THS4121ID is designated NC (No Connect) and is not bonded internally. It must remain unconnected on the PCB-neither tied to GND nor VDD-to avoid parasitic coupling or unintended current paths that could degrade common-mode rejection or introduce offset drift in the THS4121ID.
Does the THS4121ID support power-down mode like the THS4120ID?
No, the THS4121ID does not include a power-down pin or circuitry. Unlike the THS4120ID-which features a PD pin enabling 120 µA quiescent current in standby-the THS4121ID operates continuously at ~13.5 mA. This fixed-bias design ensures consistent settling behavior and eliminates turn-on delay (4.8 µs) or output transient issues associated with power cycling the THS4121ID.
Can the THS4121ID drive a 50-Ω transmission line directly?
No, the THS4121ID should not drive a 50-Ω load directly. Its specified 800-Ω load condition ensures optimal distortion and bandwidth. For 50-Ω systems, place a 20–50 Ω series resistor at each output (VOUT+, VOUT−) to isolate capacitance, improve stability, and provide source termination-per TI's Figure 21 recommendation for driving capacitive or low-impedance loads with the THS4121ID.
How is VOCM used when interfacing the THS4121ID to an ADC with no VREF output?
When the target ADC lacks a VREF output, VOCM on the THS4121ID must be driven by an external precision voltage source-typically VDD/2 generated via matched 1% resistors or a dedicated reference buffer. TI specifies VOCM must remain within 0.35 V to (VDD – 0.1 V); for 3.3-V operation, this is 0.35 V to 3.2 V. A 0.1-µF bypass capacitor is mandatory at the VOCM pin to suppress noise coupling into the THS4121ID output common-mode.
What thermal considerations apply to the THS4121ID in MSOP PowerPAD™ (DGN) package?
The THS4121ID in DGN package requires soldering its exposed thermal pad to a dedicated PCB copper pour connected to internal ground or thermal vias. Failure to do so raises junction temperature beyond 125°C under 13.5-mA quiescent load, degrading distortion and accelerating long-term reliability failure. TI's SLMA002 technical brief defines minimum pad size, via count, and copper area requirements to achieve the rated θJC = 4.7°C/W for the THS4121ID DGN variant.
THS4121ID Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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-SOIC
THS4121ID FAQ
1.How can I place an order for THS4121ID through Aetrix?
Please submit a Request for Quotation (RFQ) for THS4121ID 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 THS4121ID reliable?
The price and inventory of THS4121ID are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for THS4121ID is usually 5 days.
3.What payment methods are accepted for THS4121ID?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for THS4121ID transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for THS4121ID?
THS4121ID orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your THS4121ID 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 THS4121ID?
For technical support, including THS4121ID datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your THS4121ID requirements.
6.How does Aetrix verify that THS4121ID is sourced from the original manufacturer or authorized distributors?
All THS4121ID 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 THS4121ID meets industry standards.
7.What is the process for return or replacement of THS4121ID?
All THS4121ID units undergo pre-shipment inspection (PSI). If there is an issue with THS4121ID, 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 THS4121ID part is unused and in its original packaging.
Return procedure for THS4121ID:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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