SBOS940A May   2019  – March 2020 OPA818

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     High-Speed Optical Front-End
  3. 3 Description
    1.     Photodiode Capacitance vs 3-dB Bandwidth
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 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 Typical Characteristics: VS = ±5 V
    7. 7.7 Typical Characteristics: VS = 6 V
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input and ESD Protection
      2. 8.3.2 Feedback Pin
      3. 8.3.3 Decompensated Architecture With Wide Gain-Bandwidth Product
      4. 8.3.4 Low Input Capacitance
    4. 8.4 Device Functional Modes
      1. 8.4.1 Split-Supply Operation (+4/–2 V to ±6.5 V)
      2. 8.4.2 Single-Supply Operation (6 V to 13 V)
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Wideband, Non-Inverting Operation
      2. 9.1.2 Wideband, Transimpedance Design Using OPA818
    2. 9.2 Typical Applications
      1. 9.2.1 High Bandwidth, 100-kΩ Gain Transimpedance Design
        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 Non-Inverting Gain of 2 V/V
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Thermal Considerations
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.3.4 Low Input Capacitance

Often two primary considerations for TIA applications are maximizing TIA closed-loop bandwidth and minimizing the total output noise to maximize Signal-to-Noise Ratio (SNR). The total input capacitance (CTOT) of TIA circuit causes a zero in the noise gain in combination with the transimpedance gain (feedback resistor, RF) at frequency 1/(2πRFCTOT). For a fixed RF, this zero is at a lower frequency for higher CTOT thus increasing the noise gain at lower frequency resulting in lower equivalent closed-loop bandwidth and higher total output noise compared to a lower CTOT. By choosing an amplifier like OPA818 that features a low input capacitance (2.4 pF combined common-mode and differential) for TIA application, the system designer can realize high closed-loop bandwidth at low total output noise or have the flexibility to choose a photodiode with relatively higher capacitance. The CTOT includes the input capacitance of the amplifier, the photodiode capacitance, and the PCB parasitic capacitance at the inverting input.