How to Calculate Equivalent Input Voltage Noise Density?

Updated Nov 17, 2020

How do I calculate equivalent input voltage noise density?

Equivalent input voltage noise density can be calculated with the following equation: 

Figure 1. Equation
For example, 50uV noise at 400kHz bandwidth would have an 80nV/root Hz equivalent voltage noise density:

Figure 2. Equation example

Additional Information

Other mathematical equation and explanation related to frequency domain, you can find in The Fundamentals of FFT-Based Signal Analysis and Measurement in LabVIEW and LabWindows/CVI.