SBOS962F April   2020  – March 2023 OPA205 , OPA2205 , OPA4205

PRODMIX  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information: OPA205
    5. 6.5 Thermal Information: OPA2205
    6. 6.6 Thermal Information: OPA4205
    7. 6.7 Electrical Characteristics: VS = ±5 V
    8. 6.8 Electrical Characteristics: VS = ±15 V
    9. 6.9 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Typical Specifications and Distributions
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input Offset Trimming
      2. 8.3.2 Lower Input Bias With Super-Beta Inputs
      3. 8.3.3 Overload Power Limiter
      4. 8.3.4 EMI Rejection
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 High-Precision Signal-Chain Input Buffer
        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 Discrete, Two-Op-Amp Instrumentation Amplifier
      3. 9.2.3 Second-Order Low-Pass Filter
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 PSpice® for TI
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.2 Lower Input Bias With Super-Beta Inputs

The OPAx205 have a super-beta input transistor architecture. In a transistor, the beta value is the ratio between the current flowing into the base and the current flowing from the collector to the emitter. A super-beta transistor is one where the beta value has been increased from several hundred to thousands. In a bipolar amplifier, the input bias current is the current flowing into the base of the input transistor pair, as well as a small leakage current that flows through the ESD diodes. A super-beta input reduces the input bias current of the amplifier. In addition, the super-beta inputs lower the input current noise that is directly related to the input bias current of the device. A comparison between the input bias current of the OPA2277 and the OPAx205 super-beta input bias currents can be seen in Figure 8-4 and Figure 8-5.

GUID-C8B375E9-3DD1-44AE-B350-A7422EA9403D-low.gifFigure 8-4 OPA2277 Input Bias Current
GUID-20210518-CA0I-BH7S-BTTJ-BVLFPJRBZLZR-low.pngFigure 8-5 OPAx205 Super-Beta Input Bias Current