SBOA362A December   2019  – October 2026 REF34 , REF34-Q1 , REF3425-EP , REF3430-EP , REF3433-EP , REF3440-EP , REF4132-Q1 , REF50 , REF5020-EP , REF5020A-Q1 , REF5025-EP , REF5025-HT , REF5025A-Q1 , REF5030A-Q1 , REF5040-EP , REF5040A-Q1 , REF5045A-Q1 , REF5050-EP , REF5050A-Q1 , REF50E , REF70

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Voltage Reference Architecture
    1. 2.1 Shunt or Series Reference
    2. 2.2 Choosing the Best System Reference
  6. 3Key Specifications for Voltage Reference
    1. 3.1 Temperature Coefficient
    2. 3.2 Initial Accuracy
    3. 3.3 0.1–10 Hz Peak-to-peak Noise
    4. 3.4 Thermal Hysteresis and Long-term Stability
    5. 3.5 Load and Line Regulation
  7. 4Method of Negative Output Design and Noise Analysis
    1. 4.1 Voltage Inverting by Level Shift using REF5025 and OPA192
    2. 4.2 Using a Buffer to Generate Negative Reference Output
    3. 4.3 A Way to Minimize the Noise
  8. 5Conclusion
  9. 6References
  10. 7Revision History

3.3 0.1–10 Hz Peak-to-peak Noise

The internally generated noise of a voltage reference causes a dynamic error that degrades the signal-to-noise ratio (SNR) of a data converter. This error reduces the estimated number of bits of resolution (ENOB). Usually, data sheets provide separate specifications for low and high-frequency noise. Broadband noise is typically specified as a RMS value in microvolts over the 10-kHz to 10-kHz bandwidth. Broadband noise is the less troublesome of the two, as it can be reduced with a large VREF bypass capacitor. Depending on the signal bandwidth the designer is interested in, broadband noise may or may not be important in a given application.