- A logarithmic unit the deciBel (dB)
is often used to express the ratio of output to input signal levels
- 0dB means zero power gain
- 3dB means a doubling of power
- 6dB : 4 times
- 10dB : 10 times
- 20dB : 100 times
- -3dB : ½
- -6dB : ¼
- -10dB : 1/10
- -20dB : 1/100
- When amplifiers and or attenuators are connected in series the overall gain in dB is calculated by adding (or subtracting) the individual dB gains