TIDUFG0 November   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
  8. 2System Overview
    1. 2.1 Block Diagram
      1. 2.1.1 PCB Rogowski Coils
      2. 2.1.2 Integrator Stage
      3. 2.1.3 Input Stage
      4. 2.1.4 Differential Amplifier Stage
      5. 2.1.5 High-Bandwidth, Low-Noise Amplifier Stage
        1. 2.1.5.1 Hybrid Integrator
        2. 2.1.5.2 Band Pass Filter
        3. 2.1.5.3 Logarithmic Amplifier
    2. 2.2 Design Considerations
      1. 2.2.1 Component Selection
      2. 2.2.2 RC Component Selection
      3. 2.2.3 Gain Setting
    3. 2.3 Highlighted Products
      1. 2.3.1 INA333
      2. 2.3.2 TLV9002
      3. 2.3.3 LM2664
      4. 2.3.4 TLV2387
      5. 2.3.5 LOG300
      6. 2.3.6 TL081H
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
      1. 3.2.1 Metering Setup
        1. 3.2.1.1 Accurate Current Source
        2. 3.2.1.2 TIDA-010987
        3. 3.2.1.3 ADS131M08 Metrology Evaluation Module
        4. 3.2.1.4 GUI
      2. 3.2.2 5kHz to 50kHz Band Pass and Logarithmic Amplifier Test Setup
        1. 3.2.2.1 Oscilloscope
        2. 3.2.2.2 Function Generator
    3. 3.3 Test Results
      1. 3.3.1 No Load Conditions
        1. 3.3.1.1 Objective
        2. 3.3.1.2 Setup
        3. 3.3.1.3 Requirements
        4. 3.3.1.4 Results
      2. 3.3.2 Starting Load Test
        1. 3.3.2.1 Objective
        2. 3.3.2.2 Setup
        3. 3.3.2.3 Requirements
        4. 3.3.2.4 Results
      3. 3.3.3 Active Power Measurements
        1. 3.3.3.1 Objective
        2. 3.3.3.2 Setup
        3. 3.3.3.3 Requirements
        4. 3.3.3.4 Results
      4. 3.3.4 Variation of Power factor
        1. 3.3.4.1 Objective
        2. 3.3.4.2 Setup
        3. 3.3.4.3 Requirements
        4. 3.3.4.4 Results
      5. 3.3.5 Variation of Voltage Test
        1. 3.3.5.1 Objective
        2. 3.3.5.2 Setup
        3. 3.3.5.3 Requirements
        4. 3.3.5.4 Results
      6. 3.3.6 Variation of Frequency
        1. 3.3.6.1 Objective
        2. 3.3.6.2 Setup
        3. 3.3.6.3 Requirements
        4. 3.3.6.4 Results
      7. 3.3.7 Band Pass
        1. 3.3.7.1 Objective
        2. 3.3.7.2 Setup
        3. 3.3.7.3 Requirements
        4. 3.3.7.4 Results
      8. 3.3.8 Logarithmic Amplifier
        1. 3.3.8.1 Objective
        2. 3.3.8.2 Setup
        3. 3.3.8.3 Requirements
        4. 3.3.8.4 Results
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
      3. 4.1.3 PCB Layout Recommendations
        1. 4.1.3.1 Layout Prints
    2. 4.2 Tools
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  11. 5About the Author

2.1.4 Differential Amplifier Stage

Since the signal from the coil is very small, a gain amplification stage is needed to improve the input signal for the ADC. The INA333 device is selected for the gain stage because of the low output noise, high CMMR, and high bandwidth at high-gain settings to be flexible for multiple applications, not just for metering applications. The amplifier uses a single resistor for setting the gain, which allows the end users to cut down on cost instead of using two resistors for gain setting in a traditional gain op-amp circuit.