OPA698 - 450MHz Voltage Limiting Amplifier | Texas Instruments
MPN: OPA698 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.42 | $5.42 |
| 10 | $4.87 | $48.70 |
| 100 | $4.22 | $422.00 |
| 500 | $3.8 | $1,900.00 |
| 1,000 | $3.42 | $3,420.00 |
Drop-in alternatives for OPA698 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
OPA699M
✅ Drop-In✓ In Stock
$7.5 / Unit
View Datasheet →OPA692IDR
⚡ Same Package📋 Reference alternative (not in catalog)
LM7171AIM
⚡ Same Package📋 Reference alternative (not in catalog)
AD811SQ/883B
⚡ Same Package✓ In Stock
$20.66 / Unit
View Datasheet →OPA698 Maximum Ratings & Electrical Characteristics
| Amplifier Type | Voltage-feedback op amp with bipolar output limiting |
| Number of Channels | 1 |
| -3dB Bandwidth (Gain +1) | 450 MHz |
| Gain Bandwidth Product | 250 MHz |
| Unity-Gain Stable | Yes |
| Limiting Voltage Accuracy | +/-10 mV |
| Overdrive Recovery Time | 1 ns |
| Slew Rate | [DATA_NEEDED: slew rate] |
| Supply Voltage Range | [DATA_NEEDED: supply voltage range] |
| Quiescent Current | [DATA_NEEDED: quiescent current] |
| Input Voltage Noise | [DATA_NEEDED: input voltage noise] |
| Operating Temperature Range | -40C to +85C (I grade) |
| Package | 8-SOIC (D) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Output Limiting | Bipolar, two buffered limiting voltage inputs |
OPA698 Pin Configuration
| Pin 1 | +VL — Positive limiting voltage input (buffered) |
| Pin 2 | -IN — Inverting input |
| Pin 3 | +IN — Non-inverting input |
| Pin 4 | V- — Negative supply |
| Pin 5 | -VL — Negative limiting voltage input (buffered) |
| Pin 6 | OUT — Limited output voltage |
| Pin 7 | V+ — Positive supply |
| Pin 8 | NC — No connection - refer to datasheet package drawing |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
OPA698 is suitable for 6 applications: High-Speed ADC Input Protection, IF/RF Receiver Signal Chains, Test and Measurement Front Ends, Video and Broadband Buffering, Pulse and Instrumentation Limiting, Communications Baseband and Filter Stages.
High-Speed ADC Input Protection
The primary application for the OPA698 is protecting signal conversion devices such as high-speed analog-to-digital converters. The OPA698's bipolar output limiting with ±10mV accuracy clamps the ADC input at precisely defined thresholds, while its 450MHz bandwidth preserves the full signal content in wideband receivers. The 1ns overdrive recovery ensures that after a clamp event, the amplifier returns to linear operation without the long saturation tails of a conventional op amp, minimizing lost data in burst or pulsed signal environments.
Recommended
IF/RF Receiver Signal Chains
In IF and RF receiver front ends, the OPA698 serves as a broadband gain stage with built-in clip protection, preventing strong adjacent-channel signals from overdriving downstream mixers, log detectors, or converters. With 450MHz bandwidth at gain +1 and 250MHz GBW, it covers wide IF bands, and the buffered limiting inputs allow the clip threshold to be adjusted dynamically. Unlike external back-to-back diode clamps, the active limiting stage adds minimal capacitance and leakage, preserving signal fidelity near the clip point.
Recommended
Test and Measurement Front Ends
Oscilloscope and instrumentation front ends benefit from the OPA698's combination of 450MHz bandwidth, unity-gain stability, and hard output clipping. The limiting inputs let designers define an absolute maximum excursion into the acquisition chain, protecting sensitive sampling circuitry from accidental overrange inputs. High linearity near the limiting threshold ensures small-signal measurements remain accurate until the clip point, and the fast 1ns recovery returns the channel to operation immediately after an overload event.
Recommended
Video and Broadband Buffering
Unity-gain stability makes the OPA698 well suited for video distribution and broadband buffering where a gain-of-1 amplifier must drive back-terminated coaxial lines. The 450MHz -3dB bandwidth supports high-definition and high data-rate video signals, while the voltage-limiting feature safeguards downstream processing ICs from pathological signal levels such as ESD-induced or fault transients at connector interfaces. The SOIC-8 package simplifies layout on standard video board footprints.
Recommended
Pulse and Instrumentation Limiting
In pulse instrumentation, nuclear and timing channels, and comparator protection circuits, the OPA698 provides gain with a deterministic clip level. The 1ns overdrive recovery is the decisive parameter: conventional op amps driven into saturation exhibit microseconds of recovery delay, while the OPA698 re-establishes linear operation in nanoseconds, preserving pulse timing accuracy. Limiting thresholds are buffered externally, enabling threshold calibration or adaptive threshold schemes under microprocessor control.
Recommended
Communications Baseband and Filter Stages
Baseband and active-filter stages in communication equipment use the OPA698 where gain blocks must tolerate out-of-band transients without latching or long settling. The unity-gain stable voltage-feedback topology supports Sallen-Key and multiple-feedback filter topologies up to hundreds of megahertz, while the built-in limiting provides a fail-safe amplitude bound for the ADC or modulator that follows. The ±10mV limiting accuracy supports gain calibration across temperature in production-trimmed designs.
Recommended
Recommended Products Summary
Engineering reference data for OPA698 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | OPA699M | OPA692IDR | LM7171AIM | AD811 |
|---|---|---|---|---|---|
| Package | 8-SOIC (D) | 8-SOIC | 8-SOIC (D) - same | 8-SOIC | 8-SOIC |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Analog Devices |
| Output Limiting | Yes, bipolar, +/-10mV | Yes | No | No | No |
| Overdrive Recovery | 1 ns | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] |
| Unity-Gain Stable | Yes | No (min gain 2) | Yes | Yes | No (min gain 10) |
| Number of Channels | 1 | 1 | 1 | 1 | 1 |
| Bandwidth / GBW | 450 MHz / 250 MHz | [DATA_NEEDED] | 750 MHz / [DATA_NEEDED] | [DATA_NEEDED] | [DATA_NEEDED] |
| Limiting Accuracy | +/-10 mV | [DATA_NEEDED] | N/A | N/A | N/A |
Key Differentiators
- Integrated bipolar output voltage limiting (vs OPA692IDR)
- Unity-gain stable at 450MHz bandwidth (vs OPA699M)
- 1ns overdrive recovery (vs LM7171AIM)
Design Notes
With 450MHz bandwidth, keep feedback paths under 10mm and use a continuous ground plane under the amplifier. Use 50-ohm controlled-impedance traces for input and output, and add a series 25-50 ohm resistor at the output when driving coaxial cable to isolate load capacitance. Decouple V+ and V- with 0.1uF ceramics placed within 3mm of the supply pins plus a 4.7uF bulk capacitor per rail.
The limiting inputs (+VL, -VL) must be driven from low-impedance, buffered sources to achieve the +/-10mV limiting accuracy specified in the TI datasheet. Do not tie limiting inputs directly to the supplies unless clipping at the rails is acceptable. Also verify the source can sink/source current when the amplifier takes control during clipping, since the buffer stage will draw transient current at the clip point.
The 8-SOIC (D) package is adequate for the OPA698's power level, but thermal and RF performance improve with at least 4 ground vias near pin 4 (V-) region and a solid unbroken ground pour. Avoid routing fast digital signals beneath the amplifier; if unavoidable, add a local ground shield plane. Refer to the TI datasheet layout section and SOIC land pattern drawing for exact footprint dimensions.
Compliance Information
RoHS compliance consistent with current TI production status on DigiKey listing; obtain formal REACH and material declarations from TI product page.
