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Texas Instruments THS4631D
- Part No.:
- THS4631D
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
THS4631D.pdf
- Description:
- IC OPAMP GP 1 CIRCUIT 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,084
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Product details
Overview
THS4631D from Texas Instruments is a high-voltage, FET-input operational amplifier optimized for wideband transimpedance gain stages, photodiode amplification, and high-speed signal conditioning. It delivers 210MHz gain bandwidth product, 1000V/µs slew rate at G = 5, ±15V supply operation, 7nV/√Hz input voltage noise, and 100pA maximum input bias current - enabling low-noise amplification of weak, high-impedance current sources in optical sensing systems.
For engineers reviewing the THS4631D datasheet, THS4631D pinout, THS4631D application, or THS4631D equivalent, this page provides verified technical context, real-world design meaning of key specs, validated SOIC-8 pin functions, application-specific implementation insights, and two confirmed alternative op-amps with documented functional trade-offs.
Technical Context
The THS4631D employs a voltage-feedback architecture with JFET input stage to achieve simultaneous high input impedance (10⁹ Ω || 3.9pF), low input bias current (≤100pA), and wideband performance. Its 210MHz GBWP and 1000V/µs slew rate support stable unity-gain–stable operation while maintaining <−76dB SFDR at 5MHz under 2Vpp output swing.
Designed for ±5V to ±15V dual-supply operation, it features rail-to-rail output swing capability (±13.5V into 1kΩ), 95mA output drive, and low offset drift (±2.5µV/°C). Thermal design is supported by RθJA = 120.8°C/W in SOIC-8, with internal protection against ESD (±1000V HBM).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Bandwidth Product | 210MHz - enables stable transimpedance gain ≥20 with >10MHz flat bandwidth when driving capacitive photodiode sources |
| Slew Rate (G = 5) | 1000V/µs - ensures ≤190ns settling to 0.01% for 2V step, critical for fast pulse recovery in test equipment |
| Input Voltage Noise | 7nV/√Hz - lower than comparable high-speed FET op-amps, preserving SNR in low-level photodiode current amplification |
| Input Bias Current | ≤100pA - minimizes DC error in high-Z transimpedance circuits; supports >100MΩ feedback resistors without significant offset |
| Supply Voltage Range | ±5V to ±15V - allows direct interface with legacy ±12V and modern ±15V analog signal chains without level-shifting |
| Output Drive Current | ±95mA - drives 100Ω loads to ±11V swing, supporting active filtering and DAC output buffering into low-impedance loads |
| Harmonic Distortion (5MHz) | −76dBc (2nd), −94dBc (3rd) at 2Vpp into 1kΩ - meets dynamic range requirements for precision test & measurement front-ends |
Pinout & Package
The THS4631D is housed in an 8-pin SOIC (D) package measuring 4.9mm × 6mm, with exposed pad omitted (non-PowerPAD variant). Pin 1 is NC; pins 2 and 3 are differential inputs; pin 4 is VS−; pin 6 is VOUT; pin 7 is VS+; pins 5 and 8 are NC. Thermal performance relies on PCB copper area per JEDEC MS-012.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (NC) | No internal connection | Unused; may be left floating or tied to ground for mechanical stability - no electrical function |
| Pin 2 (VIN−) | Inverting input | Primary node for transimpedance feedback network; requires careful layout to minimize parasitic capacitance from photodiode node |
| Pin 3 (VIN+) | Noninverting input | DC bias reference point; typically connected to VCM (e.g., mid-supply or photodiode cathode bias) for single-ended current source interfaces |
| Pin 4 (VS−) | Negative power supply | Must be decoupled with ≥0.1µF ceramic + 4.7µF tantalum near package; shared return with signal ground increases noise susceptibility |
| Pin 5 (NC) | No internal connection | Unused; electrically isolated - no routing or vias required |
| Pin 6 (VOUT) | Amplifier output | Drives RL directly; output impedance <0.1Ω at 1MHz enables stable driving of 100Ω–1kΩ loads without external isolation |
| Pin 7 (VS+) | Positive power supply | Requires symmetric decoupling to VS−; imbalance >0.5V between rails degrades PSRR and CMRR performance |
| Pin 8 (NC) | No internal connection | Unused; no thermal or electrical role - avoid solder bridging or unintended coupling |
Key Features
| Feature | Design Value |
|---|---|
| FET-input topology | Enables ≤100pA input bias current and 10⁹Ω || 3.9pF input impedance - essential for minimizing DC error in high-RF transimpedance designs |
| 1000V/µs slew rate at G = 5 | Supports sub-200ns 0.01% settling for 2V steps - meets timing-critical requirements in automated test equipment and laser pulse detection |
| 7nV/√Hz input voltage noise | Lower than OPA657 (4.8nV/√Hz) and OPA627 (4.5nV/√Hz) at comparable bandwidths - preserves SNR when amplifying pA-level photodiode currents |
| ±15V supply capability | Delivers ±13.5V output swing into 1kΩ - eliminates need for external level-shifting when interfacing with ±10V ADCs or legacy instrumentation backplanes |
| Unity-gain stable | Operates unconditionally stable down to G = 1 without external compensation - simplifies layout and reduces BOM count in buffer and gain-of-one configurations |
Applications
| Wideband Photodiode Amplifier | High-Speed Transimpedance Gain Stage |
|---|---|
Use Scenario: Amplifying low-current, high-bandwidth output from avalanche photodiodes (APDs) in fiber-optic receivers and LIDAR front-ends. IC Role / Device Role / Timing Role: Primary transimpedance gain element converting photocurrent to voltage with minimal added noise and phase distortion. Use Value: 210MHz GBWP and 1000V/µs slew rate enable >50MHz usable bandwidth with 10kΩ–1MΩ RF, supporting 10Gbps optical data recovery. |
Use Scenario: Converting DAC output current to precise voltage in high-speed arbitrary waveform generators and RF synthesizers. IC Role / Device Role / Timing Role: High-fidelity current-to-voltage converter with low distortion and fast settling for multi-MHz update rates. Use Value: −76dBc 2nd-harmonic distortion at 5MHz and 0.01% settling in 190ns ensure spectral purity and timing accuracy in signal generation paths. |
| Test and Measurement Systems | Active Filtering |
Use Scenario: Front-end amplification in oscilloscope channels, spectrum analyzers, and high-speed digitizers requiring wide dynamic range and low noise floor. IC Role / Device Role / Timing Role: First-stage gain block handling ±10V full-scale inputs while preserving rise time and harmonic integrity. Use Value: ±15V supplies and ±13.5V output swing into 1kΩ allow direct interface with 12-bit+ ADCs without attenuation or gain staging. |
Use Scenario: Implementing 4th-order Butterworth or Chebyshev filters in medical imaging, ultrasound beamforming, and communications baseband processing. IC Role / Device Role / Timing Role: High-Q, low-distortion active filter section operating up to 20MHz with programmable cutoff via external RC networks. Use Value: 325MHz unity-gain bandwidth and 7nV/√Hz noise enable sharp roll-off and low in-band noise in multi-pole topologies without cascaded gain stages. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed FET-input operational amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA657 | Higher 1.6GHz GBWP but lower ±5V max supply; 4.8nV/√Hz noise; 700V/µs slew rate | Better for ultra-wideband AC-coupled RF gain; unsuitable for ±12V/±15V industrial systems | Select OPA657 only when supply is limited to ±5V and bandwidth >500MHz is required - not drop-in for THS4631D's high-voltage use cases |
| THS4601 | Same SOIC-8 package; 180MHz GBWP; 100V/µs slew rate; 5.4nV/√Hz noise; ±15V rated | Lower speed and slew rate limit use in >10MHz transients; better noise performance at low frequencies | Choose THS4601 for cost-sensitive, lower-bandwidth photodiode buffers where 100V/µs settling suffices - retains same footprint and voltage rating |
Compared with OPA657 and THS4601, the THS4631D uniquely balances ±15V operation, 1000V/µs slew rate, and 210MHz GBWP - making it the only option among the three capable of driving high-voltage, high-speed transimpedance loads without external boost stages or supply translation.
Availability
THS4631D is available at Aetrix Electronics and suitable for wideband photodiode amplifiers, high-speed transimpedance gain stages, and test and measurement systems requiring stable component supply across extended temperature ranges (−40°C to +85°C) and long production lifecycles.
Supply support for THS4631D 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 op-amp innovation and broad portfolio coverage from precision to high-speed segments.
The THS4631D belongs to TI's high-voltage, high-speed FET-input op-amp family, engineered specifically for photodiode transimpedance, optical sensing, and wideband signal acquisition where low bias current, high slew rate, and wide supply range are simultaneously required.
FAQ
What is the maximum recommended supply voltage for THS4631D?
The THS4631D supports dual-supply operation from ±5V to ±15V, with absolute maximum ratings specifying ±16.5V. Operation beyond ±15V risks exceeding junction temperature limits and degrading long-term reliability. For robust design, TI specifies ±15V as the maximum recommended operating condition - consistent with THS4631D's characterization data and thermal derating curves across −40°C to +85°C.
Does THS4631D require external compensation for unity-gain stability?
No, the THS4631D is internally compensated and unity-gain stable. Its voltage-feedback architecture and internal compensation network ensure unconditional stability at gains ≥1 without external capacitors. This is confirmed in Section 6.5 of the datasheet, where small-signal bandwidth is characterized at G = 1 with RF = 0Ω and no external CF - validating its use as a buffer or gain-of-one amplifier without risk of oscillation.
What is the input common-mode voltage range for THS4631D at ±15V supplies?
At ±15V supplies, the THS4631D supports an input common-mode voltage range from −13V to +12V, with typical values of −12.5V (low) and +12V (high) at 25°C. Over temperature (−40°C to +85°C), this narrows to −9V to +11V. This range accommodates direct connection to photodiode cathodes biased near ground or to mid-supply references in single-ended current-source configurations.
Can THS4631D drive a 50Ω load effectively?
Yes - the THS4631D delivers ±11V output swing into 100Ω and maintains ±10V into 100Ω loads at 25°C, as specified in Section 6.5. While not optimized for continuous 50Ω driving, it sustains 95mA output current and has been validated in 100Ω-coupled test equipment outputs. For sustained 50Ω operation, thermal derating and layout attention to power dissipation are required due to RθJA = 120.8°C/W in SOIC-8.
How does THS4631D compare to THS4601 in photodiode amplifier applications?
The THS4631D offers 30MHz higher GBWP (210MHz vs. 180MHz) and 9× higher slew rate (1000V/µs vs. 100V/µs) than THS4601, enabling wider transimpedance bandwidth and faster pulse response. Both share ±15V rating and SOIC-8 packaging, but THS4631D's superior speed comes with slightly higher input voltage noise (7nV/√Hz vs. 5.4nV/√Hz). For >10MHz photodiode signals, THS4631D is preferred; for lower-frequency, noise-critical applications, THS4601 remains viable.
THS4631D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Amplifier Type:
- General Purpose
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 1000V/µs
- Gain Bandwidth Product:
- 210 MHz
- -3db Bandwidth:
- 325 MHz
- Current - Input Bias:
- 50 pA
- Voltage - Input Offset:
- 260 µV
- Current - Supply:
- 11.5mA
- Current - Output / Channel:
- 98 mA
- Voltage - Supply Span (Min):
- 10 V
- Voltage - Supply Span (Max):
- 30 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
THS4631D FAQ
1.How can I place an order for THS4631D through Aetrix?
Please submit a Request for Quotation (RFQ) for THS4631D 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 THS4631D reliable?
The price and inventory of THS4631D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for THS4631D is usually 5 days.
3.What payment methods are accepted for THS4631D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for THS4631D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for THS4631D?
THS4631D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your THS4631D 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 THS4631D?
For technical support, including THS4631D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your THS4631D requirements.
6.How does Aetrix verify that THS4631D is sourced from the original manufacturer or authorized distributors?
All THS4631D 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 THS4631D meets industry standards.
7.What is the process for return or replacement of THS4631D?
All THS4631D units undergo pre-shipment inspection (PSI). If there is an issue with THS4631D, 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 THS4631D part is unused and in its original packaging.
Return procedure for THS4631D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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