SNAA320B November   2019  – January 2024 LM4040-N , LM4050-N , LM4120 , LM4128 , LM4128-Q1 , LM4132 , LM4132-Q1 , REF102 , REF1925 , REF1930 , REF1933 , REF1941 , REF20-Q1 , REF200 , REF2025 , REF2030 , REF2033 , REF2041 , REF2125 , REF2912 , REF2920 , REF2925 , REF2930 , REF2933 , REF2940 , REF3012 , REF3020 , REF3025 , REF3030 , REF3033 , REF3033-Q1 , REF31-Q1 , REF3112 , REF3120 , REF3125 , REF3130 , REF3133 , REF3140 , REF3212 , REF3212-EP , REF3220 , REF3220-EP , REF3225 , REF3225-EP , REF3230 , REF3230-EP , REF3233 , REF3240 , REF3312 , REF3318 , REF3320 , REF3325 , REF3330 , REF3333 , REF34-Q1 , REF3425 , REF3425-EP , REF3430 , REF3430-EP , REF3433 , REF3433-EP , REF3440 , REF3440-EP , REF3450 , REF35 , REF4132 , REF4132-Q1 , REF5010 , REF5020 , REF5020-EP , REF5020A-Q1 , REF5025 , REF5025-EP , REF5025-HT , REF5025A-Q1 , REF5030 , REF5030A-Q1 , REF5040 , REF5040-EP , REF5040A-Q1 , REF5045 , REF5045A-Q1 , REF5050 , REF5050-EP , REF5050A-Q1 , REF54 , REF6125 , REF6133 , REF6141 , REF6145 , REF6150 , REF6225 , REF6230 , REF6233 , REF6241 , REF6245 , REF6250 , REF70 , TL431LI , TL432LI , TLV431

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. Introduction
  5. Analog-to-Digital Converter Error
  6. Voltage Reference DC Error
    1. 3.1 Initial Accuracy and Solder Shift
    2. 3.2 Temperature Drift
    3. 3.3 Line Regulation
  7. DC Error Calculations
  8. Calibration
  9. Voltage Reference Noise Error
    1. 6.1 1/f Noise
    2. 6.2 Broadband Noise
    3. 6.3 Power Supply Rejection Ratio
    4. 6.4 Noise Example
  10. Dynamic Error (Voltage Reference Driving Capability)
  11. Low Power Applications
  12. References
  13. 10Revision History

Analog-to-Digital Converter Error

Understanding voltage reference specifications is necessary to evaluate the right voltage reference for the signal chain application. The main errors affecting the signal chain elements such as an ADC are gain error, noise error, and dynamic error. In ADCs, the gain error is a static error that effects every sample in a continuous sampling period of an ADC and can be reduced or eliminated with calibration. Noise error is an error that affect every sample independently and randomly and is inherent to semiconductor devices and architectures. Examples of noise error are 1/f noise and broadband noise. In ADCs, the noise affects all the measurements and cannot be eliminated but can be attenuated through filtering or by using digital processing techniques. Dynamic error is an error that is caused by fast switching voltage rails or change in load current. This is often associated with the input rails of the ADC but dynamic error also applies to any fast switching on output of the voltage reference. Dynamic error in this document is focused around droop error which is related to the data converter architecture and voltage reference output stage. Gain, noise, and dynamic errors are affected by the voltage reference performance. Table 2-1 covers general guidelines on voltage reference to ADC/DAC pairings but there is still flexibility based on system requirements. The background behind these choices is covered in this document.

Table 2-1 Example Voltage Reference Recommendation to Data Converters
ADC RESOLUTIONADC RECOMMENDATIONDAC RESOLUTIONDAC RECOMMENDATIONVOLTAGE REFERENCE RECOMMENDATION
10-bADS70428-bDAC43608TL431LI, TLV431
12-bADS7138,

ADS7038

10-bDAC53608LM4040-N, LM4050-N, REF30
14-b to 16-b

ADS795X, ADS1118

12-bDAC61402REF31, REF33, REF4132, REF35
16-b to 18-b

ADS7066, ADS1120

14-b to 16-bDAC8802, DAC82002REF34, REF35, REF50
18-b+ADS8900B, ADS127L0116-b+DAC11001A,

DAC11001B

REF70, REF54

24-b

ADS131ML08

REF70, REF54

32-b

ADS1285, ADS1262

REF70, REF54