Industry White Paper

dB or not dB? Everything You Ever Wanted to Know About Decibels But Were Afraid to Ask…

May 06, 2021 by Rohde & Schwarz Download PDF

Application Note Overview

%, dB, dBm and dB (µV/m) are important concepts that every engineer should understand in his (or her) sleep. Because if he does not, he is bound to be at a disadvantage in his work. When these terms come up in discussions with customers or colleagues, he will have trouble focusing on the real issue if he is busy wondering whether 3 dB means a factor of 2 or 4 (or something else). It is well worth the effort to review these concepts from time to time and keep familiar with them.

While this Application Note is not intended as a textbook, it will help to refresh your knowledge of this topic if you studied it before or provide a decent introduction if it is new to you.

You Will Learn:

  • Why use decibels in our calculations?
  • Conversion from decibels to percentage and vice versa
  • Using dB values in computations
  • What do we measure in decibels?
  • A few numbers worth knowing

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1 Comment
  • M
    mstoynov September 05, 2021

    Can decibels be a decimal fraction, for example 6.25 dB?  Or in that case to choose the closest value like 6dB?
    I am trying to calculate the CMRR of the second stage of the instrumental amplifier and the value obtained is 6.25dB.

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