SLVAG05 October   2025 TPS7A56 , TPS7A57 , TPS7A94 , TPS7A96

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction to LDO Noise and Noise Measurement
    1. 1.1 LDO Noise and LDO Noise Representation
    2. 1.2 Measuring LDO Noise Using a Spectrum Analyzer
  5. 2Solution for Measuring an Ultra-Low Noise LDO (Noise Amplifier Requirements)
    1. 2.1 Estimating the Maximum Noise for the Amplifier
    2. 2.2 Estimating the Amplifier Needed Gain
    3. 2.3 Selecting the Amplifier Circuit Feedback Resistor Values
    4. 2.4 The Amplifier Input/Output DC Blocking Filters
    5. 2.5 Verifying the Designed Amplifier Performance
  6. 3Conclusion
  7. 4References

2 Solution for Measuring an Ultra-Low Noise LDO (Noise Amplifier Requirements)

Note: Before diving into the design details of the noise amplifier, take time to consider how the noise of the amplifier combines with the noise of the LDO and analyzer, as discussed earlier.

Since the noise of the analyzer is already higher than the noise of the LDO by a significant margin (as show in Figure 1-3), the noise of the LDO and the amplifier can be safely considered first. Once the noise of the required amplifier is determined, then we can consider the necessary amplifier gain second.