
Principles of Analog Electronics
196
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So in this way
➜ The gains (or the losses by attenuation) can be summed instead of multiplied.
➜ Negative decibels represent attenuations, positive decibels represent gains.
➜ The measure scale is “compressed” (for example the enormous interval
1 μW–100 W is equal to “only” 80 dB).
According to the denition, expressing the gain G in dB,
, we get the
following:
➜ If
⇒
.
➜ If
⇒
.
➜ If
⇒
3
dB
=−
.
➜ If
⇒
60
B
dB
=
Therefore 0 dB means that the circuit has produced neither gains nor losses on
the signal; 3 dB means that in the output ...