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Texas Instruments OPA656UG4
- Part No.:
- OPA656UG4
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
OPA656UG4.pdf
- Description:
- IC VOLTAGE FEEDBACK 1 CIRC 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,556
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Product details
Overview
OPA656UG4 from Texas Instruments is a unity-gain stable, FET-input voltage-feedback operational amplifier optimized for ultra-low-noise transimpedance and high-speed data acquisition front-ends. It delivers 550MHz unity-gain bandwidth, 6nV/√Hz input voltage noise, and 2pA input bias current, enabling precision optical signal conditioning in photodiode-based OTDR and oscilloscope front-ends.
For engineers reviewing the OPA656UG4 datasheet, OPA656UG4 pinout, OPA656UG4 application, or OPA656UG4 equivalent, this page provides verified specifications, SOIC-8 package mapping, real-world transimpedance design context, and validated alternative options for high-bandwidth, low-distortion analog signal chains.
Technical Context
The OPA656UG4 employs a JFET-input stage on a high-speed complementary bipolar process, achieving unity-gain stability without external compensation while maintaining 230MHz gain-bandwidth product and 150MHz large-signal bandwidth (2VPP). Its input stage features 10¹²Ω || 0.4pF common-mode impedance and 10¹⁰Ω || 2.6pF differential impedance - critical for minimizing photodiode capacitance interaction in transimpedance configurations.
It operates from ±5V (±6V max) over –40°C to +85°C, with 11.7–16.7mA quiescent current and 400V/µs slew rate. The device uses internal ESD protection diodes to both supplies, supporting ≤10mA continuous input overdrive current - requiring external series resistors only when driven by ±12V sources.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Unity-gain bandwidth | 550MHz - enables stable buffer operation up to UHF frequencies without phase-margin degradation |
| Gain-bandwidth product | 230MHz - defines maximum closed-loop bandwidth at higher gains (e.g., 23MHz at G = +10) |
| Input voltage noise | 6nV/√Hz - dominates integrated noise in transimpedance applications above ~100kHz |
| Input bias current | 2pA (max) - minimizes DC error and leakage-induced drift in high-impedance photodiode nodes |
| Large-signal bandwidth | 150MHz (2VPP) - supports fast pulse acquisition in DAQ and active probe front-ends |
| Harmonic distortion | –80dBc HD2 / –100dBc HD3 at 5MHz (2VPP, 200Ω) - ensures fidelity in test & measurement signal paths |
| Supply range | ±5V (8V–12V total) - compatible with standard dual-rail lab and instrumentation power systems |
Pinout & Package
The OPA656UG4 is supplied in an 8-pin SOIC (D package), 4.9mm × 6mm body size, with exposed pad not present. Pin 1, 5, and 8 are no-connect (NC); pins 2 and 3 serve as inverting and noninverting inputs respectively; pins 4 and 7 connect to negative and positive supply rails; pin 6 is the output.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 5, 8 | No internal connection | Unused terminals - must remain unconnected; no routing or grounding required |
| 2 | Inverting input (VIN–) | High-impedance node for feedback network attachment in transimpedance or inverting configurations |
| 3 | Noninverting input (VIN+) | DC reference point; tied to ground or bias voltage - no bias resistor needed due to <20pA input bias current |
| 4 | Negative power supply (–VS) | Return path for internal circuitry; requires local 0.1μF + 6.8μF decoupling per datasheet layout guidelines |
| 6 | Output (VOUT) | Capable of ±3.5V swing into 100Ω; drives 50Ω test loads directly with minimal matching networks |
| 7 | Positive power supply (+VS) | Primary power rail; decoupling identical to –VS; supports ±5V nominal operation |
Key Features
| Feature | Design Value |
|---|---|
| Unity-gain stable architecture | Eliminates need for external compensation components in photodiode TIA and unity-gain buffer designs |
| JFET input stage | Delivers 10¹²Ω input impedance and sub-20pA bias current - essential for low-leakage optical sensor interfaces |
| Low input voltage noise density | 6nV/√Hz enables high-sensitivity transimpedance amplification where diode capacitance dominates noise shaping |
| High slew rate | 400V/µs supports clean 2VPP step response with 1.3ns rise time - critical for active probe and digitizer front-end fidelity |
| Industrial temperature range | Specified from –40°C to +85°C - validated for deployment in medical analyzers and field-deployable test equipment |
Applications
| Optical Time-Domain Reflectometry (OTDR) | Oscilloscope Front-End Amplifier |
|---|---|
Use Scenario: Detecting weak backscattered light pulses from fiber-optic cables over distances up to 100km. IC Role / Device Role / Timing Role: Transimpedance amplifier converting photodiode current to high-fidelity voltage signal with minimal added noise and phase distortion. Use Value: 6nV/√Hz input voltage noise and 150MHz large-signal bandwidth preserve pulse edge integrity and dynamic range for accurate fault location. |
Use Scenario: Conditioning high-frequency analog signals before ADC sampling in real-time digital storage oscilloscopes. IC Role / Device Role / Timing Role: Unity-gain buffer and wideband gain stage driving 50Ω coaxial traces with minimal group delay variation. Use Value: 550MHz unity-gain bandwidth and –100dBc HD3 at 5MHz ensure signal fidelity up to Nyquist frequency of 2.5GS/s sampling systems. |
| Medical Laser Pulse Detection | Active Differential Probe |
Use Scenario: Capturing nanosecond-scale laser pulses in flow cytometry and fluorescence lifetime imaging systems. IC Role / Device Role / Timing Role: Low-noise, high-speed amplifier in photomultiplier tube or avalanche photodiode signal chain. Use Value: 2pA input bias current prevents baseline shift during long integration windows; 400V/µs slew rate resolves sub-10ns pulses. |
Use Scenario: High-impedance, low-capacitance probing of high-speed digital or RF circuits without loading effects. IC Role / Device Role / Timing Role: Input-stage amplifier providing >1MΩ input impedance and <1pF input capacitance in differential configuration. Use Value: JFET input and 10¹²Ω || 0.4pF input impedance minimize circuit disturbance; 1.3ns rise time preserves signal timing accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed, low-noise op-amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA814IDBVR | Higher GBW (250MHz), faster slew rate (750V/µs), lower voltage noise (5.3nV/√Hz), same 1-V/V minimum stable gain | Better suited for >200MHz small-signal applications with tighter settling requirements; less optimized for transimpedance than OPA656UG4 | Select OPA814IDBVR when prioritizing speed over input bias current - its 5pA max IB is 2.5× higher than OPA656UG4's 2pA |
| OPA659UB | Higher GBW (350MHz), higher input voltage noise (8.9nV/√Hz), 1-V/V minimum stable gain, specified for ±6.5V operation | Targeted at higher-voltage, higher-bandwidth buffers; lacks OPA656UG4's ultra-low IB and optimized TIA noise floor | Choose OPA659UB only when 350MHz GBW is mandatory and 8.9nV/√Hz noise is acceptable - not a drop-in replacement for photodiode front-ends |
Compared with OPA814IDBVR and OPA659UB, the OPA656UG4 uniquely balances ultra-low input bias current (2pA), low input voltage noise (6nV/√Hz), and unity-gain stability - making it the preferred choice for precision transimpedance amplifiers where photodiode leakage and integrated noise dominate system SNR.
Availability
OPA656UG4 is available at Aetrix Electronics and suitable for optical time-domain reflectometry (OTDR), oscilloscope front-end amplification, and medical laser pulse detection requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for OPA656UG4 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 heritage in precision amplifiers and high-speed signal chain solutions.
The OPA656UG4 belongs to TI's OPA high-speed precision op-amp family, engineered specifically for transimpedance and test & measurement front-end applications demanding simultaneous low noise, high bandwidth, and dc accuracy.
FAQ
What is the maximum supply voltage for the OPA656UG4?
The OPA656UG4 supports a total supply voltage range of 8V to 12V, corresponding to ±4V to ±6V dual-supply operation. Absolute maximum ratings specify ±6.5V, but recommended operating conditions limit continuous use to ±6V. Exceeding ±6V risks reliability degradation and is not supported across the full –40°C to +85°C temperature range. The OPA656UG4 must be operated within these bounds to maintain specified distortion, bandwidth, and offset performance.
Does the OPA656UG4 require external compensation for unity-gain stability?
No, the OPA656UG4 is internally compensated for unity-gain stability and does not require external compensation components. Its voltage-feedback architecture and JFET input stage are designed to remain stable with closed-loop gains ≥1 V/V. This eliminates the need for feedback capacitors or gain-setting resistors solely for stability - simplifying transimpedance amplifier layouts and improving high-frequency phase margin in photodiode applications.
Can the OPA656UG4 be used in single-supply configurations?
Yes, the OPA656UG4 supports single-supply operation, though its input common-mode range extends only to within ~2.1V of the negative rail and ~2.75V below the positive rail at 25°C. For reliable single-supply use, the input must be biased within this window - typically using a mid-rail reference. Output swing is similarly limited: ±3.5V into 100Ω with dual ±5V supplies, so single-supply designs require careful headroom planning and level-shifting if interfacing with ground-referenced ADCs.
What is the input capacitance of the OPA656UG4 and why does it matter in transimpedance designs?
The OPA656UG4 has 2.6pF differential-mode and 0.4pF common-mode input capacitance - totaling 3.0pF at the input node. In transimpedance amplifiers, this capacitance interacts with photodiode junction capacitance (e.g., 20pF) and feedback resistor to form a pole that limits bandwidth and causes peaking. Accurate modeling of this 3.0pF value is essential for calculating optimal feedback capacitor (CF) to achieve Butterworth response - as shown in the OPA656UG4's typical OTDR application circuit.
How does the OPA656UG4 compare to the OPA656U in terms of specifications?
The OPA656UG4 is the SOIC-8 packaged, tape-and-reel version of the OPA656 - identical in electrical specifications, thermal characteristics, and pinout to the OPA656U (which denotes the same SOIC-8 variant in different packaging or marking). Both share identical gain-bandwidth (230MHz), noise (6nV/√Hz), and input bias current (2pA) specs. The "G4" suffix indicates TI's green (lead-free, RoHS-compliant) packaging standard, with no functional or parametric difference from the base OPA656U part number.
OPA656UG4 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:
- Voltage Feedback
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 295V/µs
- Gain Bandwidth Product:
- 230 MHz
- -3db Bandwidth:
- 500 MHz
- Current - Input Bias:
- 2 pA
- Voltage - Input Offset:
- 250 µV
- Current - Supply:
- 14mA
- Current - Output / Channel:
- 70 mA
- Voltage - Supply Span (Min):
- 8 V
- Voltage - Supply Span (Max):
- 12 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
OPA656UG4 FAQ
1.How can I place an order for OPA656UG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA656UG4 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 OPA656UG4 reliable?
The price and inventory of OPA656UG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA656UG4 is usually 5 days.
3.What payment methods are accepted for OPA656UG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA656UG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA656UG4?
OPA656UG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA656UG4 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 OPA656UG4?
For technical support, including OPA656UG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA656UG4 requirements.
6.How does Aetrix verify that OPA656UG4 is sourced from the original manufacturer or authorized distributors?
All OPA656UG4 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 OPA656UG4 meets industry standards.
7.What is the process for return or replacement of OPA656UG4?
All OPA656UG4 units undergo pre-shipment inspection (PSI). If there is an issue with OPA656UG4, 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 OPA656UG4 part is unused and in its original packaging.
Return procedure for OPA656UG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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