Electronic – do we use dB to represent the difference between two voltages


For example, the passband of a LC resonant circuit is the differences of frequency at +3db and -3db.

Why do we prefer dB?

Best Answer

Many processes in nature are either of logarithmic nature (like human senses) or have a great dynamic range.

Describing them on a logarithmic scale and expressing differences in dB has several advantages:

  • often the absolute difference doesn't matter, but the ratio (that's what dB is used for) does (e.g. signal-to-noise ratio)
  • smaller numbers can be used
  • there's an approximately linear relation between measurement and perceived sensation
  • chained attenuations or amplifications can be expressed by addition instead of multiplication (easier to calculate in the head)

Here's another video about it.