SBOA585 March   2024 ADS127L11 , ADS127L11 , ADS127L21 , ADS127L21 , PGA855 , PGA855

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1PGA855 and ADS127L21, 24-Bit, Delta-Sigma ADC Driver Circuit
  5. 2PGA855 Analog Front-End Filters
  6. 3ADS127Lx1 Delta-Sigma ADC and Digital Filter
  7. 4Approximate PGA855 Intrinsic Noise Analysis
    1. 4.1 Simplified Noise Model for the PGA855
    2. 4.2 PGA855 Spectral Noise Density vs Frequency
    3. 4.3 PGA855 Effective Noise Bandwidth
    4. 4.4 PGA855 Low Frequency (1/f) Noise Calculation
    5. 4.5 PGA855 Voltage Broadband Noise
    6. 4.6 PGA855 Current Noise and Source Resistance
    7. 4.7 PGA855 Total Noise
  8. 5PGA855 and ADS127Lx1 System Noise
  9. 6PGA855 and ADS127Lx1 SNR and Noise Calculator
  10. 7PGA855 and ADS127Lx1 FFT Measured Performance
  11. 8Summary
  12. 9References

4.5 PGA855 Voltage Broadband Noise

To calculate the broadband noise contribution of the PGA855, multiply the square-root of the PGA855 noise bandwidth with the input-referred voltage noise density (eNI) specification. The PGA855 data sheet provides the broadband noise density at 1kHz as a function of the PGA gain on the electrical characteristics table.

Equation 11 solves the RTI broadband noise and Table 7-6 shows the calculated broadband noise contribution of the PGA855 as a function of gain.

Equation 11. EnBBRTI  = eni ×ENBW
Table 4-2 PGA855 Input-Referred Voltage Broadband Noise
PGA GAIN
(V/V)		eni
(nV / √Hz)		fH
(Hz)		EnBB(RTI)
(µVRMS)
0.1251684550035.8
0.25844550017.9
0.542455009.0
121.6455004.6
212.6455002.7
48.6455001.8
88455001.7
167.8455001.7