SBAA201A March   2013  – March 2023 ADS1120 , ADS1120-Q1 , ADS1147 , ADS1148 , ADS114S06 , ADS114S06B , ADS114S08 , ADS114S08B , ADS1220 , ADS122C04 , ADS1247 , ADS1248 , ADS124S06 , ADS124S08

 

  1.   RTD Ratiometric Measurements and Filtering Using the ADS1148 and ADS1248 Family of Devices
  2.   Trademarks
  3. 1Introduction
  4. 2Low-Pass Filter Design Considerations in Ratiometric Measurements
    1. 2.1 Resistor and Capacitor Component Selection
  5. 3Noise Performance Using the ADS1248 in the Ratiometric Configuration
    1. 3.1 Noise Performance Using Mismatched RC Filters
    2. 3.2 Noise Performance Using The Four-Wire Configuration with Matched RC Filters
    3. 3.3 Noise Measurements Using the Three-Wire Configuration with Matched RC Filters
    4. 3.4 Other Considerations
  6. 4Conclusion
  7. 5References
  8. 6Revision History

3 Noise Performance Using the ADS1248 in the Ratiometric Configuration

Using matched RC filters at the input path and the reference path results in a better ratiometric cancellation over the entire signal range. The following subsections illustrate the effect on noise performance when the device is set up using unmatched filters, and also provide several ratiometric circuit examples using matched filters. The noise versus input signal plots are also shown.