SBOS946 September   2020 INA848

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and 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
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Topology
      2. 8.3.2 Input Common-Mode Range
      3. 8.3.3 Input Protection
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Filter Pin
        1. 9.1.1.1 RC Filter Network
        2. 9.1.1.2 RLC Filter Network
      2. 9.1.2 Input Bias Current Return Path
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Reference Pin
        2. 9.2.2.2 Noise Analysis
          1. 9.2.2.2.1 Reference Voltage Noise Contribution
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2.2 Noise Analysis

Low-noise instrumentation amplifiers such as the INA848 are designed to serve stringent and sensitive applications, such as surgical tools, microphones or other precision monitoring systems. A througough noise analysis is a key element in the design process.

TI`s super-beta transistors offer the benefits of low voltage noise and low current noise, thus allowing the INA848 excellent noise performance.

Figure 9-6 shows a simplified noise model including the gain stages of the INA848.

GUID-20200825-CA0I-NKDW-RFWL-ZPJSHSRBLJQG-low.svg Figure 9-6 Simplified Noise Model

To get the total input-referred noise, eni, consider the source resistance seen by the positive and negative input pins of the instrumentation amplifier. The key elements that must be considered for a noise analysis in an instrumenation amplifier are:

  • Current noise density ini1of the INA, see Section 7.5
  • Voltage noise denisty eni1 of the INA, see Section 7.5
  • Voltage noise density caused by source resistance ini× Rin
  • Resistor noise from source resistance enRin , given by: √Rin × 4.04 nV/√Hz
  • Reference voltage noise enref

The noise sources are uncorrelated (that is, the noise signal is unpredictable). The result of mutliple uncorrelated noise sources is the square root of the sum of their squares (RSS). Thus, the total RTI noise density, eni, in
nV/√Hz can be derived from the following equation:

Equation 5. GUID-20200825-CA0I-08WR-PTW8-SZGCCDV2SNHM-low.gif