OPA644U - 500MHz Current-Feedback Op Amp | Texas Instruments
料号： OPA644U ✓ 量产中OPA644U 概述
A current-feedback operational amplifier is a voltage-input, voltage-output amplifier whose feedback impedance establishes the closed-loop gain. It belongs to the operational-amplifier hierarchy within analog and mixed-signal ICs. Unlike a voltage-feedback amplifier, the OPA644U is optimized for high-speed applications in which gain bandwidth, output-drive capability, slew rate, and feedback-component selection strongly influence signal fidelity.
Principal features include 2500 V/µs slew rate, 0.008% differential gain error, 0.009° differential phase error, -85 dBc low distortion, 500 MHz bandwidth, and a 2.0 MΩ open-loop transimpedance. The amplifier is unity-gain stable and supports fast 12-bit settling to 0.01%. These characteristics make it suitable for wideband analog signal conditioning, data-conversion interfaces, video, communications, instrumentation, and test equipment.
OPA644U uses a current-feedback topology whose closed-loop response depends on the external feedback resistor and termination network. High bandwidth and slew rate provide rapid signal transitions, while the specified low differential gain and phase error support accurate amplification of high-frequency waveforms. Designers should still validate stability, bandwidth, output swing, and distortion against their actual gain, load, supply, and feedback configuration.
Typical applications include video distribution, high-speed instrumentation, communications receivers, analog-to-digital and digital-to-analog converter interfaces, active filters, and wideband test equipment. The 8-pin SOIC package makes the device suitable for conventional surface-mount assembly, although high-speed layouts require short traces, controlled impedance, and careful decoupling.
The main design consideration is feedback-network compatibility. Current-feedback amplifiers require resistor values chosen for the target closed-loop gain, and improper feedback impedance can alter bandwidth or induce peaking. Input and output networks should be evaluated experimentally, with supply bypassing placed close to the device pins.
This page consolidates verified distributor availability, exact manufacturer characteristics, same-family replacement analysis, and practical high-speed layout guidance to support faster component selection and safer PCB implementation.
直接替换替代料： OPA644U ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
OPA641U
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
OPA642U
✅ 直接替换 ⚠️ 规格未核验📋 参考替代料（不在目录中）
OPA644U 最大额定值与电气特性
| Amplifier Type | Current-feedback operational amplifier |
| Bandwidth | 500 MHz |
| Slew Rate | 2500 V/µs |
| Differential Gain Error | 0.008% |
| Differential Phase Error | 0.009 degrees |
| Low Distortion | -85 dBc |
| Open-Loop Transimpedance | 2.0 MΩ |
| Gain Stability | Unity-gain stable |
| 12-Bit Settling | 0.01% |
| High Linearity | Specified in manufacturer datasheet |
| Number of Terminals | 8 |
| Package Code | SOP |
| Terminal Form | Gull wing |
| Package Shape | Rectangular |
| Temperature Grade | Industrial |
| 安装类型 | Surface mount |
| Verified Price | $8.62 as of 2026-10-30 |
| Stock Quantity | 1.520 units as of 2026-10-30 |
OPA644U rectangular 引脚配置指南
OPA644U（rectangular 封装）的引脚配置。 该模拟元件具有输入、输出和电源引脚。请参阅制造商数据手册以了解失调调零、补偿和使能引脚配置。适用于信号调理和放大器电路。
暂无详细引脚数据： OPA644U.
请参阅 数据手册 以查看完整引脚配置。
典型应用
OPA644U 适用于 6 应用s: High-Speed Data Converter Interface, Video Signal Amplification, Communications Receiver Front End, Precision Analog Instrumentation, Active Filtering and Waveform Shaping, Broadband Test and Measurement.
High-Speed Data Converter Interface
The OPA644U fits ADC and DAC interface circuits that require a wideband, low-distortion buffer. Its 500 MHz bandwidth preserves high-frequency signal content, while the 2500 V/µs slew rate supports rapid output transitions. The specified 0.01% settling for a 12-bit signal is particularly useful when the converter front end must settle rapidly between code transitions. In a typical design, the amplifier is placed between the converter and an external sampling or termination network. Engineers should verify that the converter’s required bandwidth, input impedance, and settling window match the OPA644U, and that the selected feedback resistor produces the intended current-feedback gain without excessive peaking.
推荐
Video Signal Amplification
OPA644U is suitable for wideband video amplification where 500 MHz bandwidth, rapid slewing, and low distortion are more important than micropower operation. Its 0.008% differential gain error and 0.009° differential phase error help maintain amplitude and phase relationships through a video distribution or gain stage. The device can drive a terminated video path when configured with the appropriate feedback impedance and output termination. Because current-feedback gain depends on the feedback resistor, the complete gain network must be evaluated for stability, return loss, and video bandwidth rather than copied from a voltage-feedback design.
推荐
Communications Receiver Front End
The OPA644U can condition moderate- and high-frequency communications signals in receivers, modems, and instrumentation. Its 500 MHz bandwidth accommodates demanding intermediate-frequency or wideband modulation paths, and the 2500 V/µs slew rate reduces large-signal waveform distortion. The -85 dBc distortion specification supports clean amplification when the source impedance, load, and gain configuration are appropriate. Designers should use short, controlled-impedance traces and place supply bypass capacitors close to the device. Receiver-chain evaluation must also include gain-bandwidth interaction, allowable noise gain, and sensitivity to input overdrive.
推荐
Precision Analog Instrumentation
OPA644U is appropriate for high-bandwidth instrumentation that must amplify small signals without excessive gain drift or phase error. The specified 0.008% differential gain error and 0.009° differential phase error provide useful control for amplitude- and phase-sensitive measurement paths. Its 500 MHz bandwidth allows the amplifier to operate as a low-impedance input buffer for sensors and conditioning networks. The device’s high speed introduces sensitivity to layout and component parasitics, so the feedback resistor, input termination, grounding, and supply decoupling should be optimized together. Calibration may also be required when the measurement accuracy approaches the amplifier’s specified error limits.
推荐
Active Filtering and Waveform Shaping
The OPA644U can serve in wideband active filters and waveform-shaping stages where the 500 MHz bandwidth and 2500 V/µs slew rate must be preserved simultaneously. Low differential gain and phase error make the device useful when the filter must maintain accurate signal relationships over a broad frequency range. In implementation, the current-feedback topology requires the feedback resistor to be selected together with the source and load impedances. Test the closed-loop response, output swing, and stability across process and temperature variation. Component self-heating, parasitic inductance, and an incorrect feedback impedance can create unexpected peaking even when the nominal bandwidth is sufficient.
推荐
Broadband Test and Measurement
OPA644U is useful in broadband test equipment requiring fast, low-distortion signal amplification. Its 500 MHz bandwidth, 2500 V/µs slew rate, and 0.01% 12-bit settling support measurements involving fast edges and high-order harmonic content. The amplifier may precede an ADC, active probe, or attenuator in a test-and-measurement signal path. For accurate results, the selected feedback resistor and termination network should be characterized at the operating frequency, and the output must remain within its voltage and current limits. The industrial-grade SOIC implementation also supports conventional surface-mount assembly while still requiring disciplined high-frequency layout.
推荐
推荐产品汇总
工程参考数据： OPA644U ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | OPA641U | OPA642U | OPA643U |
|---|---|---|---|---|
| Package | 8-pin SOIC | 8-pin SOIC | 8-pin SOIC | 8-pin SOIC |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Amplifier Architecture | Current feedback | Current feedback | Current feedback | Current feedback |
关键差异点
- 500 MHz bandwidth for wideband signal integrity （对比 OPA641U)
- 2500 V/µs slew rate for large-signal fidelity （对比 OPA642U)
- Specified low gain and phase error （对比 OPA643U)
- Documented 12-bit settling performance （对比 OPA641U)
设计说明
Keep the OPA644U feedback loop physically small and connect each feedback component directly to the relevant pins. Place input and output decoupling capacitors close to the device with short ground returns. At 500 MHz, PCB trace inductance and parasitic capacitance can materially alter closed-loop response, so use a continuous ground plane, minimize series resistance, and avoid long stubs or unnecessary test-pad structures.
Select the feedback resistor from the manufacturer’s recommended values for the intended closed-loop gain and source impedance. Current-feedback amplifiers do not follow the simple gain-bandwidth behavior of voltage-feedback devices. After selecting the nominal value, verify stability, gain peaking, phase margin, bandwidth, and distortion with the actual source and load impedances because parasitic capacitance can create unintended peaking.
Use the supply range and bypass requirements stated in the manufacturer datasheet; these values were not present in the supplied search extracts and must be confirmed before implementation. Place the supply bypass capacitor on the same side of the PCB as the device and connect it to the ground reference through a very short path. Verify output swing and load current at the operating supply voltage rather than assuming the amplifier can reach its rails.
Do not treat an 8-pin SOIC footprint match as proof that another current-feedback amplifier is a drop-in replacement. Changing amplifier family members can alter gain-bandwidth behavior, recommended feedback resistance, output drive, noise gain, and stability. Confirm the numbered pinout, supply currents, common-mode range, output swing, and compensation requirements, then bench-test the complete channel before production release.
合规信息
The supplied evidence identifies an industrial-grade 8-terminal SOP but does not explicitly state RoHS, REACH, lead-free, halogen-free, conflict-minerals, or AEC-Q100 status. The AEC-Q100 field is not applicable because the OPA644U is identified as an industrial-grade operational amplifier rather than an automotive-qualified variant.
