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Texas Instruments OPA656UBG4
- Part No.:
- OPA656UBG4
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
OPA656UBG4.pdf
- Description:
- IC VOLTAGE FEEDBACK 1 CIRC 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,041
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Product details
Overview
OPA656UBG4 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 systems.
For engineers reviewing the OPA656UBG4 datasheet, OPA656UBG4 pinout, OPA656UBG4 application, or OPA656UBG4 equivalent, this page provides verified specifications, SOIC-8 package layout, real-world transimpedance design context, and validated alternative options for test & measurement, OTDR, and medical analyzer signal chains.
Technical Context
The OPA656UBG4 employs a low-noise JFET input stage on a high-speed complementary bipolar process, achieving unity-gain stability without external compensation. Its 230MHz gain-bandwidth product and 150MHz large-signal bandwidth (2VPP) support wideband noninverting and inverting configurations with minimal phase shift up to 100MHz.
Designed for transimpedance applications, it combines 10¹²Ω || 0.4pF common-mode input impedance with ultra-low 6nV/√Hz voltage noise and 5fA/√Hz current noise at 100kHz-enabling high dynamic range in optical front-ends where diode capacitance dominates noise shaping.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Unity-gain bandwidth | 550MHz - enables stable operation as a high-fidelity buffer or follower in GHz-range signal paths |
| Gain-bandwidth product | 230MHz - defines maximum closed-loop bandwidth achievable at higher gains (e.g., 23MHz at G=10) |
| Input voltage noise | 6nV/√Hz - dominant noise contributor in transimpedance amplifiers with >10kΩ feedback resistors |
| Input bias current | 2pA (max) - ensures negligible DC error in high-impedance photodiode bias networks |
| Large-signal bandwidth | 150MHz @ 2VPP - supports fast pulse acquisition in oscilloscope front-ends and DAQ systems |
| Supply voltage range | ±5V nominal (±6V max) - compatible with standard dual-rail lab instrumentation power rails |
| Input offset voltage | ±0.6mV (high-grade spec) - enables sub-mV DC accuracy in calibrated optical sensor interfaces |
Pinout & Package
The OPA656UBG4 is packaged in an 8-pin SOIC (D package), 4.9mm × 6mm body size, with exposed pad not present. Pin 1 is NC; pins 2 and 3 are VIN– and VIN+; pin 4 is –VS; pin 6 is VOUT; pin 7 is +VS; pins 1, 5, and 8 are no-connect.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1, 5, 8 | No internal connection | Unused terminals - must be left floating or grounded per layout best practices; no routing required |
| 2 | Inverting input | Primary feedback node in transimpedance and inverting amplifier configurations |
| 3 | Noninverting input | DC reference point in single-supply designs; tied to mid-rail or ground in inverting mode |
| 4 | Negative power supply | Return path for bias current and output sinking; requires local 0.1μF + 6.8μF decoupling |
| 6 | Amplifier output | Drives 100Ω loads directly; output impedance <0.01Ω at DC, rising to ~10Ω at 100MHz |
| 7 | Positive power supply | Source for output sourcing and input stage bias; symmetric ±5V rail recommended |
Key Features
| Feature | Design Value |
|---|---|
| Unity-gain stable architecture | Eliminates need for external compensation in photodiode TIA and probe buffer circuits |
| JFET input stage | Delivers 10¹²Ω input impedance and 2pA bias current - critical for high-Z optical sensors |
| Low harmonic distortion | –80dBc HD2 / –100dBc HD3 @ 5MHz, 2VPP into 200Ω - preserves signal fidelity in spectrum analysis |
| Industrial temperature range | –40°C to +85°C operation - qualified for medical analyzers and field-deployable OTDR equipment |
| ESD robustness | ±2000V HBM - withstands handling in automated test equipment assembly lines |
Applications
| High-Speed Data Acquisition | Optical Time-Domain Reflectometry |
|---|---|
Use Scenario: Digitizing fast transient signals from piezoelectric sensors or RF sampling front-ends. IC Role / Device Role / Timing Role: Front-end buffer and gain stage preceding 12-bit+ ADCs, preserving rise time and SNR. Use Value: 150MHz large-signal bandwidth ensures <1% amplitude error on 10ns pulses; 6nV/√Hz noise maintains >70dB SNR at 10MHz. |
Use Scenario: Detecting backscattered light pulses in fiber-optic cable fault localization. IC Role / Device Role / Timing Role: Transimpedance amplifier converting photodiode current to voltage with minimal group delay variation. Use Value: 550MHz unity-gain bandwidth supports sub-nanosecond pulse response; low input capacitance (3pF total) minimizes peaking in 100kΩ TIA designs. |
| Medical Analyzers | Oscilloscope Active Probes |
Use Scenario: Amplifying weak electrochemical or fluorescence detector outputs in blood gas or immunoassay platforms. IC Role / Device Role / Timing Role: Low-noise, high-Z preamplifier interfacing with microamp-level current sources. Use Value: 2pA input bias current prevents baseline drift in µA-range measurements; ±0.6mV offset enables <0.1% linearity over 100mV full-scale. |
Use Scenario: High-impedance, low-capacitance signal conditioning in 1GHz-class passive/active probe tips. IC Role / Device Role / Timing Role: Unity-gain buffer isolating probe tip from scope input, maintaining signal integrity up to 500MHz. Use Value: 550MHz bandwidth ensures <0.5dB flatness to 400MHz; SOIC-8 package allows compact PCB layout with <0.3pF parasitic capacitance. |
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 | 250MHz GBW, 5.3nV/√Hz noise, 750V/µs slew rate - higher speed but less DC precision | Better for >100MHz small-signal AC-coupled paths; less suitable for DC-stable transimpedance | Select when bandwidth >230MHz is mandatory and offset drift <6μV/°C is secondary |
| OPA659UB | 350MHz GBW, 8.9nV/√Hz noise, 2550V/µs slew rate - wider bandwidth but higher noise and lower input Z | Preferred for ultra-fast pulse amplification; not optimal for low-current photodiode detection | Choose for >300MHz signal chain segments where voltage noise <10nV/√Hz is acceptable |
Compared with OPA656UBG4, OPA814IDBVR trades 20MHz GBW margin for lower noise and faster settling, while OPA659UB sacrifices input impedance and voltage noise for extreme slew rate-making OPA656UBG4 the optimal balance for precision transimpedance and calibrated DAQ front-ends.
Availability
OPA656UBG4 is available at Aetrix Electronics and suitable for high-speed data acquisition, optical time-domain reflectometry, and medical analyzer applications requiring stable component supply across industrial temperature ranges and long production lifecycles.
Supply support for OPA656UBG4 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 signal-chain solutions.
The OPA656UBG4 belongs to TI's high-speed precision op-amp product line, engineered specifically for transimpedance amplification, optical test equipment, and metrology-grade front-ends demanding unity-gain stability and ultra-low noise.
FAQ
What is the maximum supply voltage for the OPA656UBG4?
The OPA656UBG4 has an absolute maximum supply voltage of ±6.5V, but its recommended operating range is ±5V (10V total). Operation at ±6V is permitted per datasheet specifications, while ±6.5V risks permanent damage. For reliable long-term use in industrial environments, maintain supply within ±5V ±5%, and always include local 0.1μF ceramic + 6.8μF tantalum decoupling on both +VS and –VS pins of the OPA656UBG4.
Can the OPA656UBG4 be used in single-supply configurations?
Yes, the OPA656UBG4 supports single-supply operation with proper input/output voltage headroom management. Its input common-mode range extends to within 2.1V of the negative rail and 2.75V below the positive rail at 25°C, and its output swings to within 1.3V of each rail under 100Ω load. To use OPA656UBG4 in single-supply mode, bias VIN+ at mid-rail (e.g., 2.5V for 5V system), ensure photodiode cathode connects to V+, and verify that signal swing remains within CMIR and output swing limits across –40°C to +85°C.
Why does the OPA656UBG4 specify both "high-grade" and standard DC parameters?
The OPA656UBG4 is offered in two screening grades: standard (OPA656U) and high-grade (OPA656UB/OPA656NB). The high-grade version tightens key DC specs - e.g., input offset voltage to ±0.6mV (vs ±1.8mV standard) and offset drift to ±6μV/°C (vs ±12μV/°C) - via post-package burn-in and 100% testing. These tighter tolerances are essential for calibrated optical instruments and medical analyzers where system-level DC accuracy must be guaranteed without user trimming. The OPA656UBG4 is the high-grade SOIC-8 variant.
How does the OPA656UBG4 achieve unity-gain stability with a FET input?
The OPA656UBG4 integrates internal frequency compensation tailored for its JFET input stage and bipolar output stage, ensuring unconditional stability at G = +1 without external components. Unlike uncompensated FET-input op-amps, its dominant-pole compensation places the unity-gain crossover at 550MHz while maintaining ≥45° phase margin across all gains ≥1. This is verified in Figure 6-19 (open-loop gain/phase) and confirmed by stable step response in Figure 6-5 - making OPA656UBG4 uniquely suited for unity-gain photodiode transimpedance amplifiers where stability margins directly impact pulse fidelity.
What layout practices are critical for optimal OPA656UBG4 performance?
For OPA656UBG4, minimize parasitic capacitance at VIN– and VIN+ by using short, direct traces; remove ground/power planes under the input nodes; place 0.1μF ceramic decoupling capacitors ≤2mm from each supply pin; and route the feedback resistor (RF) directly from VOUT to VIN– with no vias. In transimpedance applications, keep photodiode anode-to-VIN– trace length <1mm and shield it from noisy digital lines. These practices prevent peaking, preserve 550MHz bandwidth, and reduce noise coupling - all validated in TI's OPA656UBG4 layout guidelines (SBOS196I, Section 8.4).
OPA656UBG4 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:
- 1 pA
- Voltage - Input Offset:
- 250 µV
- Current - Supply:
- 14mA
- Current - Output / Channel:
- -
- 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
OPA656UBG4 FAQ
1.How can I place an order for OPA656UBG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA656UBG4 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 OPA656UBG4 reliable?
The price and inventory of OPA656UBG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA656UBG4 is usually 5 days.
3.What payment methods are accepted for OPA656UBG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA656UBG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA656UBG4?
OPA656UBG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA656UBG4 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 OPA656UBG4?
For technical support, including OPA656UBG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA656UBG4 requirements.
6.How does Aetrix verify that OPA656UBG4 is sourced from the original manufacturer or authorized distributors?
All OPA656UBG4 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 OPA656UBG4 meets industry standards.
7.What is the process for return or replacement of OPA656UBG4?
All OPA656UBG4 units undergo pre-shipment inspection (PSI). If there is an issue with OPA656UBG4, 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 OPA656UBG4 part is unused and in its original packaging.
Return procedure for OPA656UBG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
OPA656UBG4 Tags
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