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Texas Instruments THS4121IDR
- Part No.:
- THS4121IDR
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
THS4121IDR.pdf
- Description:
- IC OPAMP DIFF 1 CIRCUIT 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,253
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Product details
Overview
THS4121IDR from Texas Instruments is a high-speed, fully differential-input/differential-output amplifier optimized for ADC driver and antialiasing filter applications in single-supply 3.3 V 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 balanced outputs rejecting common-mode noise in precision data acquisition circuits.
For engineers reviewing the THS4121IDR datasheet, THS4121IDR pinout, THS4121IDR application, or THS4121IDR equivalent, key selection criteria include differential output swing compliance with 800 Ω load, VOCM-controlled DC level shifting, thermal management of the MSOP PowerPAD™ package, and resistor matching requirements for CMRR preservation.
Technical Context
The THS4121IDR implements a true fully differential signal path from input to output using TI's submicron CMOS process, enabling symmetrical gain and phase response that cancels second-harmonic distortion and improves PSRR. Its VOCM pin sets the common-mode output voltage independently, supporting midrail biasing for single-supply ADC interfacing without transformers.
Unlike the THS4120, the THS4121IDR omits the power-down (PD) pin-confirmed by pinout diagrams and electrical specifications-making it a fixed-operation, low-latency amplifier suited for continuous-sampling systems where quiescent current stability (13.5 mA typical) is prioritized over dynamic power gating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Bandwidth (–3 dB) | 100 MHz - supports baseband signals up to Nyquist frequency of 50 MSPS ADCs without attenuation. |
| Slew Rate | 55 V/µs - enables clean reproduction of fast transient signals such as pulse-shaped sensor outputs or DAC steps. |
| THD @ 1 MHz | –75 dB (2 VPP) - ensures <0.006% harmonic distortion in high-fidelity analog front-ends feeding 12–16-bit ADCs. |
| Input Noise | 5.4 nV/√Hz @ 10 kHz - contributes minimal noise floor degradation when driving high-resolution converters. |
| CMRR | 96 dB (typ) - rejects coupled noise on shared PCB traces or ground planes in mixed-signal layouts. |
| Supply Range | 3.3 V single supply - eliminates need for dual rails; VOCM defaults to VDD/2 (1.65 V) for seamless ADC reference alignment. |
| Quiescent Current | 13.5 mA (typ) - fixed bias enables predictable thermal behavior and simplifies power budgeting in always-on systems. |
Pinout & Package
The THS4121IDR is housed in an 8-pin MSOP PowerPAD™ (DGN) package with exposed thermal pad on underside, requiring solder connection to PCB copper for thermal dissipation per TI SLMA002 guidelines. The package is RoHS-compliant and rated MSL-2.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN− | Inverting Input | Differential input node; requires matched trace length and impedance to VIN+ to preserve CMRR. |
| VOCM | Output Common-Mode Control | Sets DC offset of both outputs; bypass with 0.1 µF capacitor to suppress noise coupling into ADC reference path. |
| VDD | Positive Supply | 3.3 V single rail; decouple with 6.8 µF tantalum + 0.1 µF ceramic placed ≤2.54 mm from pin. |
| VOUT+ | Positive Differential Output | Drives one leg of differential ADC input; output impedance ~1 Ω enables direct interface to 800 Ω loads. |
| VIN+ | Non-Inverting Input | Differential input node; symmetry with VIN− critical for harmonic cancellation and PSRR performance. |
| NC | No Connect | Internally unused; must remain unconnected per datasheet to avoid parasitic coupling or latch-up risk. |
| GND | Analog Ground Reference | Low-inductance return path; isolated from digital ground except at single-point star connection near supply decoupling. |
| VOUT− | Negative Differential Output | Complementary output to VOUT+; balanced amplitude and phase ensure rejection of even-order harmonics at ADC input. |
Key Features
| Feature | Design Value |
|---|---|
| Fully differential I/O architecture | Enables 2× dynamic range vs. single-ended amplifiers: e.g., 2 VPP output drives 1 VPP differential ADC inputs without clipping. |
| High CMRR (96 dB typ) | Maintains signal integrity in noisy industrial environments where ground bounce or EMI couples equally to both inputs. |
| VOCM-controlled output level shift | Allows precise alignment of amplifier output common-mode voltage to ADC reference (e.g., AVDD/2), eliminating level-shifting circuitry. |
| Optimized for capacitive loads | Internal compensation supports stable operation with ≥20 Ω series output isolation resistor, enabling direct drive of ADC input capacitance (typically 10–20 pF). |
| PowerPAD™ thermal package | MSOP-DGN's exposed die pad reduces θJA to 58.4°C/W, permitting 1.71 W power dissipation at 25°C ambient-critical for sustained high-speed operation. |
Applications
| Medical Ultrasound Front-End | Industrial Data Acquisition System |
|---|---|
Use Scenario: Amplifying low-amplitude echo signals from piezoelectric transducers before digitization at 40–60 MSPS. IC Role / Device Role / Timing Role: Differential ADC driver providing gain, common-mode level shift, and antialias filtering interface to 14-bit SAR ADC. Use Value: 100 MHz bandwidth captures full ultrasound bandwidth; –75 dB THD preserves weak echo fidelity; VOCM alignment avoids DC offset errors in beamforming algorithms. | Use Scenario: Conditioning sensor outputs (strain gauges, RTDs) in programmable logic controller (PLC) analog input modules. IC Role / Device Role / Timing Role: Precision differential transmitter converting single-ended sensor voltage to noise-immune differential pair for isolation barrier transmission. Use Value: 96 dB CMRR rejects 50/60 Hz mains noise coupled across isolation barriers; 5.4 nV/√Hz noise floor maintains >100 dB SNR in 24-bit delta-sigma ADC paths. |
| Communications Baseband Processing | Test & Measurement Equipment |
Use Scenario: Driving IQ modulator inputs in software-defined radio (SDR) transceivers operating up to 20 MHz baseband. IC Role / Device Role / Timing Role: High-linearity differential output stage ensuring accurate I/Q balance and carrier suppression. Use Value: –75 dB THD and symmetric slew rate minimize image frequency generation; matched output impedance enables 50 Ω transmission line termination. | Use Scenario: Signal conditioning in portable oscilloscope front-ends requiring wide bandwidth and low distortion for 100 MHz real-time sampling. IC Role / Device Role / Timing Role: Antialiasing filter amplifier preceding 1 GS/s ADC, configured with external RC network per Figure 22. Use Value: 100 MHz small-signal bandwidth allows sharp filter roll-off; low output impedance (<1 Ω) ensures minimal interaction with filter component tolerances. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fully differential amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| THS4131IDGNR | 150 MHz BW, 51 V/µs SR, 1.3 nV/√Hz noise, ±2.5 to ±15 V split supply only | Requires dual supply; higher bandwidth suits >65 MSPS ADCs but lacks single-supply VOCM flexibility | Select when higher speed and lower noise justify dual-rail complexity and board area for supply regulation. |
| LMH5401RTVR | 1.2 GHz BW, 3000 V/µs SR, 2.3 nV/√Hz, supports 3.3 V single supply with VOCM, but no PowerPAD package | Higher bandwidth introduces layout sensitivity; lacks integrated thermal pad, limiting sustained power handling | Select for RF sampling applications >250 MSPS where THS4121IDR's 100 MHz BW is insufficient, accepting tighter layout constraints. |
Compared with THS4121IDR, THS4131IDGNR offers higher bandwidth and lower noise but mandates split supplies, while LMH5401RTVR delivers RF-grade speed at the cost of thermal robustness and increased PCB layout rigor-making THS4121IDR optimal for cost-sensitive, thermally constrained 3.3 V industrial/data acquisition designs.
Availability
THS4121IDR is available at Aetrix Electronics and suitable for medical ultrasound front-ends, industrial PLC analog input modules, and communications baseband processing requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.
Supply support for THS4121IDR 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 signaling in data converter interfaces-emphasizing low distortion, common-mode noise immunity, and single-supply operability in space-constrained industrial and medical systems.
FAQ
What is the function of the VOCM pin on the THS4121IDR?
The VOCM pin on the THS4121IDR sets the common-mode voltage of both differential outputs. When left unconnected, it defaults to VDD/2 (1.65 V for 3.3 V supply), enabling direct interfacing with ADCs that require midrail-biased differential inputs. A 0.1 µF bypass capacitor is mandatory to prevent noise injection into the output common-mode path, as specified in the TI SLOS319D datasheet.
Does the THS4121IDR support power-down functionality like the THS4120?
No, the THS4121IDR does not include a power-down (PD) pin. Unlike the THS4120, which features a dedicated PD pin requiring a 10-kΩ pullup resistor, the THS4121IDR operates continuously with a fixed quiescent current of 13.5 mA (typ). This design choice prioritizes signal path consistency and eliminates turn-on delay (4.8 µs) and output impedance variation associated with power-down states.
What package type is used for the THS4121IDR, and how should the thermal pad be handled?
The THS4121IDR uses the MSOP PowerPAD™ (DGN) package with an exposed thermal pad on the underside. Per TI SLMA002 guidelines, this pad must be soldered to a dedicated PCB copper pour connected to a thermal plane or ground layer via multiple vias. Failure to do so risks exceeding the 125°C maximum junction temperature, degrading distortion performance and long-term reliability.
Can the THS4121IDR drive a 50 Ω transmission line directly?
The THS4121IDR should not drive a 50 Ω load directly due to stability concerns. For 50 Ω systems, TI recommends placing a 50 Ω series resistor at each output (VOUT+ and VOUT−) to isolate capacitive loading and provide source-end impedance matching. This configuration prevents high-frequency ringing while maintaining signal integrity, as validated in the "Driving a Capacitive Load" section of the SLOS319D datasheet.
What is the recommended resistor tolerance for feedback networks used with the THS4121IDR?
Texas Instruments specifies 1% tolerance or better for all resistors in the THS4121IDR feedback network (Rf and Rg). Resistor mismatch degrades CMRR, PSRR, and second-harmonic cancellation-key advantages of the fully differential architecture. Precision matching preserves the –75 dB THD performance and ensures balanced output amplitude, especially critical in high-resolution data acquisition applications.
THS4121IDR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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
THS4121IDR FAQ
1.How can I place an order for THS4121IDR through Aetrix?
Please submit a Request for Quotation (RFQ) for THS4121IDR 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 THS4121IDR reliable?
The price and inventory of THS4121IDR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for THS4121IDR is usually 5 days.
3.What payment methods are accepted for THS4121IDR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for THS4121IDR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for THS4121IDR?
THS4121IDR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your THS4121IDR 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 THS4121IDR?
For technical support, including THS4121IDR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your THS4121IDR requirements.
6.How does Aetrix verify that THS4121IDR is sourced from the original manufacturer or authorized distributors?
All THS4121IDR 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 THS4121IDR meets industry standards.
7.What is the process for return or replacement of THS4121IDR?
All THS4121IDR units undergo pre-shipment inspection (PSI). If there is an issue with THS4121IDR, 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 THS4121IDR part is unused and in its original packaging.
Return procedure for THS4121IDR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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