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Texas Instruments OPA861IDR
- Part No.:
- OPA861IDR
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
OPA861IDR.pdf
- Description:
- IC OPAMP TRANSCOND 1 CIRC 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,017
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Product details
Overview
OPA861IDR from Texas Instruments is a wideband bipolar operational transconductance amplifier (OTA) with 80MHz open-loop bandwidth (G = +5), 900V/µs slew rate, 95mA/V transconductance, ±5V supply operation, and external quiescent current control via pin 1. It serves as a voltage-controlled current source in high-speed video, RF, and active filter signal paths.
For engineers reviewing the OPA861IDR datasheet, OPA861IDR pinout, OPA861IDR application, or OPA861IDR equivalent, this page delivers verified specifications, SO-8 package layout, real-world use cases in broadcast equipment and wideband LED drivers, and two confirmed alternative OTAs with documented functional trade-offs.
Technical Context
The OPA861IDR implements a three-terminal OTA architecture-B (high-Z base-like input), E (low-Z emitter-like input/output), and C (high-Z collector-like current output)-with self-biased bipolar core enabling zero-output current at zero B–E voltage. Its transconductance is externally adjustable via RADJ (pin 1 to –VS), directly scaling bandwidth, gain, and quiescent current.
It supports common-emitter, common-base, and common-collector configurations without DC biasing networks. The C-output delivers bipolar current centered at zero for AC-coupled inputs, and its transconductance remains stable over temperature when RADJ is fixed-unlike discrete transistors-due to internal compensation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Bandwidth | 80MHz at G = +5, VO = 200mVPP, RL = 500Ω - enables 20MHz video signal amplification with <4.4ns rise/fall time |
| Slew Rate | 900V/µs - supports full-scale 5V step response within 5.6ns, critical for pulse integrity in data acquisition |
| Transconductance (gm) | 95mA/V min (±10mV input, RC = 50Ω) - defines linear small-signal gain and sets noise floor for precision current-mode circuits |
| Quiescent Current | 5.4mA typ at RADJ = 250Ω - balances power vs. bandwidth; adjustable from 1mA to 6mA via external resistor |
| Input Voltage Noise | 2.4nV/√Hz @ >100kHz - low enough for high-SNR IF amplification without degrading system noise figure |
| Supply Voltage Range | ±2.0V to ±6.3V - supports dual-rail operation in legacy ±5V systems and low-voltage portable designs |
| Operating Temp | –45°C to +85°C - qualified for industrial video infrastructure and outdoor communications equipment |
Pinout & Package
OPA861IDR is packaged in an SO-8 surface-mount package (JEDEC MS-012AC, 150°C/W θJA). Pin 1 is IQ Adjust (connect to –VS via RADJ); pins 2 and 3 are E and B inputs; pin 4 is NC; pins 5 and 6 are –VS and +VS; pin 7 is NC; pin 8 is C output.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IQ Adjust) | Quiescent current control node | Connects to –VS via external resistor (250Ω typical) to set total IQ from 1–6mA; determines gm, bandwidth, and noise |
| 2 (E) | Emitter input/output terminal | Low-impedance (≈10.5Ω) bidirectional node; used for degeneration, feedback return, or current sink/source path |
| 3 (B) | Base input terminal | High-impedance (455kΩ || 2.1pF) voltage-controlled node; input offset ±3mV max; drives transconductance |
| 4 (NC) | No connect | Not internally bonded; must remain unconnected per TI design rules |
| 5 (–VS) | Negative supply rail | Accepts –2.0V to –6.3V; absolute max –6.5V; bypass with 0.1µF + 2.2µF solid tantalum |
| 6 (+VS) | Positive supply rail | Accepts +2.0V to +6.3V; absolute max +6.5V; bypass identically to –VS |
| 7 (NC) | No connect | Not internally bonded; must remain unconnected |
| 8 (C) | Collector output terminal | High-impedance current source/sink (54kΩ || 2pF); outputs ±15mA max; compliance ±4.7V at ±1mA |
Key Features
| Feature | Design Value |
|---|---|
| External IQ control via pin 1 | Enables dynamic bandwidth/gain/noise optimization using single resistor-no PCB redesign needed when tuning performance |
| Self-biased OTA core | Eliminates external bias networks required by discrete transistors, reducing component count and thermal drift in AGC loops |
| Constant gm over temperature | Transconductance stability preserves gain accuracy across –45°C to +85°C, unlike BJTs whose β and gm vary significantly |
| Bipolar current output | C-terminal delivers symmetrical ±15mA sourcing/sinking, enabling true AC-coupled integrators and differential current-mode filters |
| Three-terminal transistor analogy | Direct mapping to common-emitter/base/collector topologies simplifies circuit reuse from discrete BJT designs into monolithic OTA layouts |
Applications
| Video Line Driver | Wideband Active Filter |
|---|---|
Use Scenario: Driving 75Ω coaxial cable in HD broadcast equipment with minimal group delay distortion across 0–10MHz. IC Role / Device Role / Timing Role: Forward amplifier (common-E configuration) with RE = 78Ω and RC = 500Ω, delivering G = +5V/V noninverting gain. Use Value: 80MHz bandwidth ensures flat frequency response up to 10MHz; 900V/µs slew rate prevents edge rounding on 1080p sync pulses. | Use Scenario: Implementing a 20kHz low-pass negative impedance converter (NIC) filter for sensor signal conditioning. IC Role / Device Role / Timing Role: OTA configured as voltage-controlled current source in NIC topology with C1/C2 network and R feedback. Use Value: Adjustable gm via RADJ allows precise Q-factor tuning; low 2.4nV/√Hz input noise preserves SNR in low-level analog front-ends. |
| High-Speed Data Acquisition | Fiber Optic LED Driver |
Use Scenario: Amplifying fast transient pulses (≤10ns rise) from photodiode arrays in LIDAR receivers. IC Role / Device Role / Timing Role: Common-base amplifier with grounded B-input and E-driven input, providing inverting gain and low input Z. Use Value: 4.4ns rise/fall time meets sub-10ns pulse fidelity requirements; ±15mA C-output drives 50Ω ADC input directly. | Use Scenario: Modulating laser diodes in 10Gbps fiber transceivers with linear current control and minimal overshoot. IC Role / Device Role / Timing Role: Current-mode driver where B-input accepts modulation voltage and C-output sources laser bias current. Use Value: 95mA/V gm enables precise µA-level current resolution; external IQ adjustment optimizes speed vs. thermal dissipation at 85°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar operational transconductance amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMH6552MA/NOPB | Current-feedback amplifier (CFA), not OTA; 1.8GHz GBW, no external gm control, fixed 12mA IQ | Used in unity-gain buffers and high-Z line drivers-not suitable for current-mode integrators or NIC filters | Select only if voltage-mode gain >100MHz and gm adjustability is unnecessary |
| THS3201DGN | Current-feedback op amp with 1.8GHz GBW, 4000V/µs slew, but no dedicated B/E/C terminals or OTA transfer function | Optimized for high-speed voltage amplification, not transconductance-based analog computation | Choose when driving capacitive loads >100pF or requiring ultra-low distortion at 100MHz, not OTA-specific functions |
Compared with OPA861IDR, LMH6552MA/NOPB offers higher bandwidth but lacks gm programmability and true OTA topology, while THS3201DGN provides superior slew rate yet cannot replace OPA861IDR in current-mode filter or AGC designs due to fundamental architecture mismatch.
Availability
OPA861IDR is available at Aetrix Electronics and suitable for video/broadcast equipment, high-speed data acquisition systems, and wideband active filter designs requiring stable component supply, long-term industrial lifecycle support, and SO-8 package compatibility.
Supply support for OPA861IDR 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, embedded processing, and high-performance signal chain solutions.
The OPA861IDR belongs to TI's high-speed operational transconductance amplifier product line, engineered for wideband systems including broadcast video, RF/IF circuitry, and precision current-mode signal processing.
FAQ
What is the maximum operating supply voltage for the OPA861IDR?
The OPA861IDR supports a maximum operating supply voltage of ±6.3V, with absolute maximum ratings at ±6.5VDC. Exceeding ±6.5V risks permanent damage. At ±5V operation, it delivers 80MHz bandwidth and 900V/µs slew rate. The OPA861IDR must be decoupled with 0.1µF ceramic and 2.2µF solid tantalum capacitors placed close to pins 5 (–VS) and 6 (+VS).
How does the IQ Adjust pin (pin 1) control transconductance in the OPA861IDR?
The IQ Adjust pin (pin 1) sets total quiescent current by connecting an external resistor (RADJ) between pin 1 and –VS. With RADJ = 250Ω, the OPA861IDR draws 5.4mA and achieves 95mA/V transconductance. Reducing RADJ increases IQ and gm; increasing RADJ decreases both. This direct gm control enables real-time bandwidth and noise optimization without changing circuit topology.
Can the OPA861IDR be used as a unity-gain buffer, and what configuration is required?
Yes, the OPA861IDR can operate as a unity-gain buffer in common-collector (emitter-follower) configuration: connect B-input (pin 3) to input signal, E-terminal (pin 2) to output, and C-output (pin 8) to load. Use RE ≥500Ω for best gain accuracy. The OPA861IDR achieves near-zero VOS (vs. several volts in BJT followers) and maintains gm stability over temperature-critical for precision buffering in control loops.
What are the key differences between the OPA861IDR and standard op amps in active filter design?
Unlike voltage-mode op amps, the OPA861IDR is a true OTA with separate B, E, and C terminals-enabling current-mode filter topologies like NICs and current-controlled biquads. Its gm is externally adjustable, allowing Q-factor and cutoff frequency tuning independent of resistor values. The OPA861IDR also provides inherent current output compliance (±4.7V) and bipolar sourcing/sinking, which standard op amps cannot replicate without additional transistors.
Is the OPA861IDR pin-compatible with other SO-8 OTAs or transconductance amplifiers?
No, the OPA861IDR has a unique SO-8 pinout optimized for its B/E/C OTA architecture: pin 1 = IQ Adjust, pin 2 = E, pin 3 = B, pins 4/7 = NC, pins 5/6 = –VS/+VS, pin 8 = C. It is not pin-compatible with LM13700, CA3080, or modern current-conveyor ICs. Any replacement requires PCB layout revision to match the OPA861IDR's terminal assignments and decoupling requirements.
OPA861IDR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Amplifier Type:
- Transconductance
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 900V/µs
- Gain Bandwidth Product:
- 80 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 1 µA
- Voltage - Input Offset:
- 3 mV
- Current - Supply:
- 5.4mA
- Current - Output / Channel:
- 15 mA
- Voltage - Supply Span (Min):
- 4 V
- Voltage - Supply Span (Max):
- 12.6 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
OPA861IDR FAQ
1.How can I place an order for OPA861IDR through Aetrix?
Please submit a Request for Quotation (RFQ) for OPA861IDR 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 OPA861IDR reliable?
The price and inventory of OPA861IDR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for OPA861IDR is usually 5 days.
3.What payment methods are accepted for OPA861IDR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for OPA861IDR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for OPA861IDR?
OPA861IDR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your OPA861IDR 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 OPA861IDR?
For technical support, including OPA861IDR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your OPA861IDR requirements.
6.How does Aetrix verify that OPA861IDR is sourced from the original manufacturer or authorized distributors?
All OPA861IDR 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 OPA861IDR meets industry standards.
7.What is the process for return or replacement of OPA861IDR?
All OPA861IDR units undergo pre-shipment inspection (PSI). If there is an issue with OPA861IDR, 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 OPA861IDR part is unused and in its original packaging.
Return procedure for OPA861IDR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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