ZHCSGM4C August   2017  – October 2023 OPA838

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics: VS = 5 V
    6. 7.6 Electrical Characteristics: VS = 3 V
    7. 7.7 Typical Characteristics: VS = 5 V
    8. 7.8 Typical Characteristics: VS = 3 V
    9. 7.9 Typical Characteristics: Over Supply Range
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input Common-Mode Voltage Range
      2. 8.3.2 Output Voltage Range
      3. 8.3.3 Power-Down Operation
      4. 8.3.4 Trade-Offs in Selecting The Feedback Resistor Value
      5. 8.3.5 Driving Capacitive Loads
    4. 8.4 Device Functional Modes
      1. 8.4.1 Split-Supply Operation (±1.35 V to ±2.7 V)
      2. 8.4.2 Single-Supply Operation (2.7 V to 5.4 V)
      3. 8.4.3 Power Shutdown Operation
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Noninverting Amplifier
      2. 9.1.2 Inverting Amplifier
      3. 9.1.3 Output DC Error Calculations
      4. 9.1.4 Output Noise Calculations
    2. 9.2 Typical Applications
      1. 9.2.1 High-Gain Differential I/O Designs
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Transimpedance Amplifier
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curve
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 TINA-TI™ Simulation Model Features
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 接收文档更新通知
    4. 10.4 支持资源
    5. 10.5 Trademarks
    6. 10.6 静电放电警告
    7. 10.7 术语表
  12.   Mechanical, Packaging, and Orderable Information

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9.2.2 Transimpedance Amplifier

A common application for a high-gain-bandwidth voltage-feedback op amp is to amplify a small photodiode current from a capacitive detector. Figure 9-7 shows the front-page transimpedance circuit with more detail. Here, a fixed –0.23 negative voltage generator (LM7705) is used on the negative supply to make sure the output has adequate headroom when the output is at 0 V. The transimpedance stage is designed here for a 2.4‑MHz flat (Butterworth) response while a simple RC post-filter band-limits the broadband noise and sets the overall bandwidth to 1 MHz. The requirements for a high-dynamic-range transimpedance (or charge) amplifier include the very low input voltage noise intrinsic to a decompensated device like the OPA838. The noise gain over frequency for this type of circuit starts out at unity gain, and then begins to peak with a single zero response. This peaking is due to the pole formed in the feedback by the feedback resistor and the total capacitance on the inverting input. That noise gain response is flattened out at higher frequencies by the feedback capacitor value to be the 1 + CS / CF capacitor ratio. This noise gain is normally a very high, allowing the decompensated OPA838 to be applied to this application. The noise gain is intentionally peaked to a high value in this application; therefore, the very low input voltage noise (1.8 nV/√Hz) of the OPA838 improves dynamic range.

GUID-83DA88D4-43C4-4AFF-86A7-E283D11F65E0-low.gif Figure 9-7 100-kΩ Wide Bandwidth Transimpedance Design