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Texas Instruments THS4121CDGK
- Part No.:
- THS4121CDGK
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
THS4121CDGK.pdf
- Description:
- IC OPAMP DIFF 1 CIRCUIT 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,157
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Product details
Overview
THS4121CDGK from Texas Instruments is a single-channel, fully differential-input/differential-output high-speed amplifier optimized for driving precision ADCs in single-supply 3.3 V systems. 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 with VOCM pin for output common-mode level control - enabling transformerless interface to differential analog-to-digital converters.
For engineers reviewing the THS4121CDGK datasheet, THS4121CDGK pinout, THS4121CDGK application, or THS4121CDGK equivalent, this page provides verified specifications, package-validated pin functions, real-world ADC driver use cases, and two confirmed alternative parts with documented functional and application differences.
Technical Context
The THS4121CDGK implements a true fully differential signal path from input to output, supporting both differential-input/differential-output and single-ended-input/differential-output configurations. Its internal architecture enables balanced output swing, inherent second-harmonic cancellation, and high common-mode rejection (96 dB typical) without external trimming.
It features a dedicated VOCM pin that sets the DC common-mode level of both outputs independently of gain configuration, with high bandwidth up to the amplifier's operating range. Unlike the THS4120, it lacks a power-down (PD) pin - confirming its role as the non-power-down variant in the THS412x family.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| –3 dB Bandwidth | 100 MHz at G = 1, defines usable small-signal frequency range for high-speed data acquisition front ends |
| Slew Rate | 55 V/µs, supports fast settling of large transient signals into ADC inputs without distortion |
| Total Harmonic Distortion | –75 dB at 1 MHz, 2 VPP output, ensures minimal spectral contamination in precision sampling applications |
| Input Voltage Noise | 5.4 nV/√Hz at 10 kHz, critical for preserving SNR when amplifying low-level sensor or RFIF signals |
| Common-Mode Input Range | 0.35 V to VDD – 0.1 V (3.2 V max at 3.3 V supply), enables direct interfacing with mid-rail-biased sources |
| Supply Voltage | 3.3 V single supply only - no split-supply operation supported per recommended conditions |
| Quiescent Current | 13.5 mA typical, determines thermal load and system power budget in always-on signal chain stages |
Pinout & Package
THS4121CDGK is housed in an 8-pin MSOP PowerPAD™ package (DGK), featuring an exposed thermal pad on the underside for enhanced heat dissipation. The PowerPAD must be soldered to a thermally conductive PCB copper plane to maintain junction temperature ≤125°C under continuous operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN−) | Inverting input | Differential input node; requires matched trace length and impedance to VIN+ for optimal CMRR |
| 2 (VOCM) | Output common-mode control | Sets DC level of both VOUT+ and VOUT−; bypass with 0.1 µF capacitor to suppress noise coupling |
| 3 (VDD) | Positive supply | 3.3 V single supply input; requires local 0.1 µF ceramic + 6.8 µF tantalum decoupling |
| 4 (VOUT+) | Positive differential output | Delivers inverted-phase signal relative to VOUT−; drives one leg of differential ADC input |
| 5 (VIN+) | Non-inverting input | Differential input node; symmetrical layout with VIN− essential to preserve balance and distortion performance |
| 6 (NC) | No connect | Internally unused; must remain unconnected and unstubbed to avoid parasitic coupling |
| 7 (GND) | Analog ground reference | Primary return path for input/output currents; tie directly to solid analog ground plane |
| 8 (VOUT−) | Negative differential output | Delivers non-inverted-phase signal relative to VOUT+; completes differential pair to ADC |
Key Features
| Feature | Design Value |
|---|---|
| Fully differential I/O architecture | Enables 2× dynamic range vs. single-ended drivers by splitting 2 VPP signal into two 1 VPP complementary outputs |
| High common-mode rejection (96 dB) | Maintains signal integrity in noisy industrial or mixed-signal environments where ground bounce or EMI couples equally to both outputs |
| VOCM pin with rail-to-rail capability | Allows precise alignment of output common-mode voltage to ADC reference (e.g., AVDD/2), eliminating level-shifting components |
| Low 5.4 nV/√Hz input noise | Preserves effective number of bits (ENOB) in 14–16-bit ADC systems by minimizing added noise floor contribution |
| Optimized for 3.3 V single supply | Eliminates need for ±1.65 V rails or charge pumps, simplifying power architecture in portable and embedded data loggers |
Applications
| High-Speed Data Acquisition Systems | Differential ADC Driver |
|---|---|
Use Scenario: Sampling wideband sensor outputs (e.g., ultrasound transducers, radar IF) at ≥10 MSPS into 14-bit SAR or sigma-delta ADCs. IC Role / Device Role / Timing Role: Front-end signal conditioner and level translator; provides gain = 1 differential drive with VOCM-aligned common-mode voltage matching ADC reference. Use Value: Enables transformerless interface while maintaining –75 dB THD and 100 MHz bandwidth - reducing BOM cost and board area vs. discrete balun solutions. |
Use Scenario: Driving the differential input of TI ADS88xx or ADI AD76xx series precision ADCs in test equipment and instrumentation. IC Role / Device Role / Timing Role: High-fidelity buffer between anti-alias filter and ADC input; settles within 60 ns to 0.1% for accurate sampling window timing. Use Value: Achieves >90 dB SFDR at 1 MHz due to balanced output structure, directly improving measured ENOB without post-processing correction. |
| Communications Baseband Processing | Single-Ended to Differential Conversion |
Use Scenario: Converting baseband I/Q signals from FPGA DACs (e.g., Xilinx Zynq RFSoC) into differential format for RF mixer input. IC Role / Device Role / Timing Role: Low-distortion current-to-voltage converter and common-mode shifter; maintains phase coherence between I and Q paths. Use Value: Delivers <–75 dBc third-order IMD at 10 MHz, ensuring clean spectral purity required for LTE/5G adjacent channel leakage ratio (ACLR) compliance. |
Use Scenario: Interfacing single-ended op-amp outputs (e.g., PGA stages) to differential-input ADCs in medical imaging front ends. IC Role / Device Role / Timing Role: Active balun with programmable VOCM; converts unbalanced signal while rejecting even-order harmonics via symmetry. Use Value: Reduces second-harmonic distortion by >15 dB compared to passive transformers, improving diagnostic image contrast resolution. |
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; not pin-compatible; higher bandwidth suits wider IF sampling but increases power (22 mA) | Select when >100 MHz bandwidth is mandatory and split supply is available; avoid for 3.3 V-only systems. |
| ADA4940-1ACPZ-R7 | 13 GHz GBW, 470 V/µs slew rate, 2.2 nV/√Hz noise, supports 3.3 V single supply, includes shutdown pin | Higher speed/noise performance; different pinout (LFCSP-8); requires revised PCB layout and bias network | Choose for ultra-low-noise, high-SFDR applications where THS4121CDGK's 5.4 nV/√Hz is insufficient; verify VOCM drive strength compatibility. |
Compared with THS4121CDGK, THS4131CDGN offers higher bandwidth but mandates dual supply and consumes nearly double the quiescent current, while ADA4940-1ACPZ-R7 delivers superior noise and speed in a smaller package but requires layout redesign and has no direct pin mapping - making THS4121CDGK optimal for cost-sensitive, 3.3 V, space-constrained ADC driver roles.
Availability
THS4121CDGK is available at Aetrix Electronics and suitable for high-speed data acquisition systems, precision ADC driver circuits, and communications baseband signal conditioning requiring stable component supply across industrial temperature ranges (0°C to 70°C).
Supply support for THS4121CDGK 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 over 50 years of innovation in high-performance signal chain components.
The THS412x family was designed specifically for high-fidelity, single-supply differential signal conditioning in data converter interfaces - prioritizing THD, bandwidth, and VOCM flexibility over general-purpose op-amp versatility.
FAQ
What is the supply voltage range for THS4121CDGK?
The THS4121CDGK operates exclusively from a single 3.3 V supply, with recommended range of 3.0 V to 3.5 V. It does not support split supplies or voltages outside this range. Operation at 3.3 V ensures specified performance including 100 MHz bandwidth, –75 dB THD, and 55 V/µs slew rate. Deviation beyond 3.5 V risks exceeding absolute maximum ratings and may cause permanent damage.
Does THS4121CDGK have a power-down feature?
No, THS4121CDGK does not include a power-down (PD) pin. That function is exclusive to the THS4120 variant. The THS4121CDGK is intended for always-on, high-fidelity signal paths where quiescent current (13.5 mA typical) is acceptable. If low-power operation is required, THS4120CDGK - which adds a PD pin and reduces current to 120 µA in shutdown - must be substituted with appropriate circuit modifications.
How should the VOCM pin be used in THS4121CDGK?
The VOCM pin on THS4121CDGK sets the DC common-mode voltage of both differential outputs. It can be tied to a stable reference (e.g., ADC VREF/2) or left floating to default to VDD/2 (1.65 V). A 0.1 µF ceramic capacitor must be placed directly from VOCM to GND to suppress noise coupling. Incorrect VOCM routing causes output imbalance and increased harmonic distortion - especially critical in 14+ bit ADC applications.
Is THS4121CDGK compatible with 800 Ω differential load impedance?
Yes, THS4121CDGK is characterized and specified with RL = 800 Ω differential load (i.e., 400 Ω per output to ground), delivering full performance including –75 dB THD at 1 MHz and 100 MHz bandwidth. Driving lower impedances (e.g., 100 Ω) increases quiescent current and may degrade distortion; higher loads (e.g., 2 kΩ) maintain specs but reduce output swing capability. Always verify thermal dissipation using the DGK package's θJA = 260°C/W rating.
What is the function of Pin 6 (NC) on THS4121CDGK?
Pin 6 on THS4121CDGK is a no-connect (NC) terminal - internally unconnected and electrically isolated. It must remain unconnected on the PCB, with no trace stubs or vias attached. Routing signals or grounding this pin introduces parasitic capacitance that degrades high-frequency stability and common-mode rejection. The NC designation is confirmed in TI's official SLOS319D datasheet pin diagram and packaging documentation.
THS4121CDGK Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- 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:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-VSSOP
THS4121CDGK FAQ
1.How can I place an order for THS4121CDGK through Aetrix?
Please submit a Request for Quotation (RFQ) for THS4121CDGK 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 THS4121CDGK reliable?
The price and inventory of THS4121CDGK are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for THS4121CDGK is usually 5 days.
3.What payment methods are accepted for THS4121CDGK?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for THS4121CDGK transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for THS4121CDGK?
THS4121CDGK orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your THS4121CDGK 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 THS4121CDGK?
For technical support, including THS4121CDGK datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your THS4121CDGK requirements.
6.How does Aetrix verify that THS4121CDGK is sourced from the original manufacturer or authorized distributors?
All THS4121CDGK 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 THS4121CDGK meets industry standards.
7.What is the process for return or replacement of THS4121CDGK?
All THS4121CDGK units undergo pre-shipment inspection (PSI). If there is an issue with THS4121CDGK, 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 THS4121CDGK part is unused and in its original packaging.
Return procedure for THS4121CDGK:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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