TIDUFC1A November   2025  – February 2026

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 ADS127L21B
      2. 2.3.2 REF81
      3. 2.3.3 REF54
      4. 2.3.4 RES21A
      5. 2.3.5 THP210
      6. 2.3.6 OPA828
  9. 3System Design Theory
    1. 3.1 Range Selection
    2. 3.2 Linearity and Low-Noise Signal Chain
    3. 3.3 Calibration
    4. 3.4 Additional System Design Considerations
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Description
      1. 4.1.1 PCB Interface
      2. 4.1.2 Input Multiplexer
      3. 4.1.3 Gain Multiplexer
      4. 4.1.4 Power Supplies
      5. 4.1.5 Clock Tree
    2. 4.2 Software Requirements
    3. 4.3 Test Setup
    4. 4.4 Test Results
      1. 4.4.1 Integral Nonlinearity Measurements
      2. 4.4.2 Noise Simulation
      3. 4.4.3 Noise Measurements
      4. 4.4.4 Conclusion
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Tools
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author
  13. 7Revision History

4.1 Hardware Description

Figure 4-1 shows the PCB design. REF81 and RES11 (U2 and U3) in the upper left provide the calibration reference voltages. TMUX6104 and OPA828 (U7 and U4) in the bottom right create the programmable gain amplifier. THP210 and ADS127L21B (U6 and U10) in the center of the board provide a linear, low-noise signal path. There are several layout choices intended to improve performance. A star-ground plane as discussed in Section 3.4 reduces errors from the large current consumption of REF81. Additionally, the traces in the differential signal path are as symmetrical as possible to reduce any errors from mismatch between the differential signals.

TIDA-010970 TIDA-010970 PCBFigure 4-1 TIDA-010970 PCB