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Texas Instruments OPA656UB
- Part No.:
- OPA656UB
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
OPA656UB.pdf
- Description:
- IC VOLTAGE FEEDBACK 1 CIRC 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:479
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Product details
Overview
OPA656UB from Texas Instruments is a unity-gain stable, FET-input operational amplifier optimized for high-dynamic-range transimpedance and precision front-end applications. It delivers 550MHz unity-gain bandwidth, 6nV/√Hz input voltage noise, ≤600μV max input offset voltage (high-grade DC spec), and operates from ±4V to ±6V supplies. It serves as the signal-conditioning core in optical time-domain reflectometry (OTDR) receivers and high-speed data acquisition analog front-ends.
For engineers reviewing the OPA656UB datasheet, OPA656UB pinout, OPA656UB application, or OPA656UB equivalent, this page provides verified package mapping (SOIC-8), confirmed JFET-input architecture, validated transimpedance performance at 100kΩ gain, real-world distortion specs (–80dBc HD2 @ 5MHz), and two field-validated alternative op-amps with documented parameter trade-offs.
Technical Context
The OPA656UB implements a voltage-feedback topology with a low-noise JFET differential pair, enabling unity-gain stability without external compensation. Its 230MHz gain-bandwidth product supports wideband closed-loop gains from 1× to 10× while maintaining ≤1dB peaking and <19ns settling to 0.02%.
It features ultra-low input bias current (≤2pA typical) and high input impedance (>10¹² Ω || 0.4pF), making it suitable for photodiode current-to-voltage conversion where diode capacitance dominates bandwidth. The device is specified across –40°C to +85°C and supports dual-supply operation with ±5V nominal rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Unity-gain bandwidth | 550MHz - enables direct buffering of >200MHz small-signal waveforms without phase margin loss |
| Input voltage noise | 6nV/√Hz - sets fundamental SNR floor in transimpedance amplifiers with ≥10kΩ feedback resistors |
| Max input offset voltage | ±0.6mV (high-grade spec) - ensures ≤0.6mV dc error in precision active probe calibration paths |
| Large-signal bandwidth | 150MHz (2VPP) - supports full-scale 100MS/s digitizer front-ends with minimal slew-induced distortion |
| Supply range | ±4V to ±6V (8V–12V total) - compatible with standard ±5V test equipment rails and industrial power domains |
| Harmonic distortion | –80dBc HD2 / –100dBc HD3 @ 5MHz, 2VPP, RL=200Ω - meets spectral purity requirements in OTDR pulse generation |
| Input bias current | ±2pA (typical) - minimizes dark-current-induced offset drift in photodiode circuits with >1GΩ effective source impedance |
Pinout & Package
OPA656UB is packaged in an 8-pin SOIC (D package), 4.9mm × 6mm body size, with exposed pad not present. Pin functions are validated per TI SBOS196I Rev F (Feb 2024).
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1, 5, 8 | No connection (NC) | Internally unconnected; must be left floating or tied to ground per layout best practice - no routing or loading required |
| 2 | Inverting input (VIN–) | High-impedance JFET node; sensitive to stray capacitance - requires guard ring and minimal trace length in transimpedance layouts |
| 3 | Noninverting input (VIN+) | DC-bias reference point; typically grounded or set via high-impedance network - input bias current ≤2pA avoids significant offset |
| 4 | Negative supply (–VS) | Return path for internal bias currents; requires local 0.1μF + 6.8μF decoupling adjacent to pin to suppress high-frequency PSRR degradation |
| 6 | Output (VOUT) | Capable of ±3.5V swing into 100Ω; output impedance <0.01Ω at DC rising to ~10Ω at 100MHz - demands controlled-impedance routing |
| 7 | Positive supply (+VS) | Primary power rail; shares same decoupling requirement as –VS - mismatched decoupling degrades CMRR above 1MHz |
Key Features
| Feature | Design Value |
|---|---|
| Unity-gain stable architecture | Eliminates need for external compensation components in 1× buffer or transimpedance configurations - reduces BOM count and layout sensitivity |
| JFET input stage | Delivers ≤2pA input bias current and >10¹² Ω input resistance - preserves signal integrity in high-impedance photodiode and sensor interfaces |
| Low 6nV/√Hz voltage noise | Enables sub-picoampere current resolution in 100kΩ transimpedance designs - critical for optical receiver sensitivity below –30dBm |
| High DC precision (high-grade) | Guarantees ≤±0.6mV VOS and ≤±6μV/°C drift - supports factory-calibrated active probes without user nulling circuitry |
| –40°C to +85°C operation | Validated performance across industrial temperature range - ensures consistent bandwidth and distortion in embedded test equipment |
Applications
| Optical Time-Domain Reflectometry (OTDR) | High-Speed Data Acquisition Front-End |
|---|---|
|
Use Scenario: Amplifying weak, nanosecond-scale return pulses from fiber-optic fault detection. IC Role / Device Role / Timing Role: Transimpedance amplifier converting photodiode current to voltage with 100kΩ gain and 4MHz bandwidth. Use Value: 6nV/√Hz input noise and 150MHz large-signal bandwidth enable detection of <–50dBm reflections with <1m spatial resolution. |
Use Scenario: Conditioning analog signals prior to 100+ MS/s ADC sampling in portable spectrum analyzers. IC Role / Device Role / Timing Role: Unity-gain buffer isolating passive anti-alias filter from ADC input, preserving transient fidelity. Use Value: 550MHz unity-gain bandwidth and <19ns settling ensure <0.02% step accuracy for 10MHz full-scale transitions. |
| Active Oscilloscope Probe | Medical Laser Pulse Detection |
|
Use Scenario: High-impedance, low-capacitance signal acquisition in 1GHz-class passive/active probe tips. IC Role / Device Role / Timing Role: First-stage amplifier in probe head, providing 10× attenuation compensation and dc offset correction. Use Value: ≤±0.6mV max VOS and ≤±6μV/°C drift allow calibrated offset stability over probe warm-up without recalibration. |
Use Scenario: Converting fast-rise-time (≤1ns) photocurrent pulses from laser-tissue interaction sensors. IC Role / Device Role / Timing Role: Wideband transimpedance amplifier with 50Ω output drive capability for 50Ω-coupled digitizers. Use Value: –100dBc HD3 at 5MHz ensures harmonic-free capture of multi-wavelength laser pulse envelopes for tissue characterization. |
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 |
|---|---|---|---|
| OPA814 | Higher GBW (250MHz), faster slew rate (750V/μs), lower voltage noise (5.3nV/√Hz), but higher input bias current (±20pA) | Better for >200MHz small-signal amplification; less suitable for ultra-high-Z photodiode nodes due to 10× higher IB | Select OPA814 when bandwidth and slew dominate over input current; choose OPA656UB when photodiode leakage or dark current is <10pA |
| OPA659 | Higher GBW (350MHz), higher voltage noise (8.9nV/√Hz), wider supply range (±6.5V), and higher input offset (±1.5mV max) | Preferred for single-supply systems up to 13V; trades noise and dc precision for raw speed and rail flexibility | Select OPA659 for 12V single-rail DAQ systems requiring >300MHz closed-loop bandwidth; retain OPA656UB for dual-rail, low-noise, precision-critical roles |
Compared with OPA814 and OPA659, the OPA656UB uniquely balances 550MHz unity-gain bandwidth with ≤2pA input bias and 6nV/√Hz noise - making it the only option among the three qualified for sub-picoampere photodiode current measurement at >10MHz bandwidth.
Availability
OPA656UB is available at Aetrix Electronics and suitable for high-speed data acquisition, optical time-domain reflectometry, and active probe design requiring stable component supply, long-term lifecycle support, and guaranteed high-grade DC specifications.
Supply support for OPA656UB 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 op-amps and high-speed signal chain solutions.
The OPA656UB belongs to TI's precision high-speed op-amp product line, engineered specifically for transimpedance amplification, optical test equipment, and metrology-grade front-ends where unity-gain stability, ultra-low noise, and guaranteed DC accuracy are mandatory.
FAQ
What is the maximum supply voltage for the OPA656UB?
The OPA656UB supports a total supply voltage range of 8V to 12V (±4V to ±6V). Absolute maximum ratings specify ±6.5V, but continuous operation above ±6V risks reliability degradation per TI SBOS196I Section 6.1. For robust long-term use in industrial environments, ±5V is the recommended nominal operating point for the OPA656UB.
Does the OPA656UB require external compensation for unity-gain stability?
No - the OPA656UB is internally compensated for unity-gain stability. Its voltage-feedback architecture guarantees stable operation with closed-loop gains ≥1 V/V without added feedback capacitors or resistor networks. This is confirmed in the device description (Section 3) and "Features" list of the official OPA656UB datasheet.
How does the OPA656UB differ from the standard OPA656 in terms of DC specifications?
The OPA656UB is the high-grade variant: it guarantees tighter DC limits - including ±0.6mV max input offset voltage (vs. ±1.8mV for standard grade) and ±6μV/°C max offset drift (vs. ±12μV/°C). These specs are validated per Section 6.6 of the OPA656UB datasheet and apply across –40°C to +85°C ambient.
Can the OPA656UB drive a 50Ω load directly?
Yes - the OPA656UB delivers ±3.5V output swing into 100Ω and maintains low distortion (–80dBc HD2) into 200Ω. Driving 50Ω is feasible with minor gain reduction and attention to layout; however, TI recommends using a series 49.9Ω resistor at the output to match 50Ω systems while protecting the OPA656UB's output stage from excessive current.
What is the validated package type for the OPA656UB ordering option?
The OPA656UB is exclusively offered in the 8-pin SOIC (D package), 4.9mm × 6mm footprint, as confirmed in TI's official packaging table (Section 11, SBOS196I). No SOT-23 (DBV) variant exists for the UB grade - only the standard OPA656 is available in DBV.
OPA656UB 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:
- 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
OPA656UB FAQ
1.How can I place an order for OPA656UB through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA656UB 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 OPA656UB reliable?
The price and inventory of OPA656UB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA656UB is usually 5 days.
3.What payment methods are accepted for OPA656UB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA656UB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA656UB?
OPA656UB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA656UB 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 OPA656UB?
For technical support, including OPA656UB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA656UB requirements.
6.How does Aetrix verify that OPA656UB is sourced from the original manufacturer or authorized distributors?
All OPA656UB 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 OPA656UB meets industry standards.
7.What is the process for return or replacement of OPA656UB?
All OPA656UB units undergo pre-shipment inspection (PSI). If there is an issue with OPA656UB, 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 OPA656UB part is unused and in its original packaging.
Return procedure for OPA656UB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
OPA656UB Tags
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