sorry for bad description, I am a beginner.

my question is just for knowledge and I did not test anything.

If I connect for example 3 amplifier , each one has 60 dB gain and 15 dBm power.

can we say simply total gain is 180 dB and total power is 15 dBm ?

or I am wrong ?

  • \$\begingroup\$ How are you connecting the amplifiers, and what do you mean by "has 15 dBm power"? Has it how? \$\endgroup\$
    – Phil Frost
    Commented Oct 21, 2014 at 17:13
  • \$\begingroup\$ in a series , 15dBm is output for one amp \$\endgroup\$
    – man abduo
    Commented Oct 21, 2014 at 17:18

1 Answer 1


The amplifier gain is the ratio of output power to input power. For example, a 20 dB power gain means that the output power will be 100 times the input power.

On the other hand, the power rating is the maximum output power the amplifier can handle. If that is 15 dBm, then the maximum output power is 32 mW (with a given distortion).

If you are connecting amplifiers in series, then the total gain (in dB) is the sum of all the individual gains. And you have to make sure that the signal level at the output of each amplifier does not exceed its power rating.

  • \$\begingroup\$ what you mean by last sentence ? do you mean the input signal should be -45 dBm to be amplified to 15 dbm to get gain 60 db ? the second amplifier will has input of 15 dbm , and already the output is 15 dbm also ! so that it mean there is no gain in second amplifier in the series ? \$\endgroup\$
    – man abduo
    Commented Oct 20, 2014 at 10:21
  • \$\begingroup\$ The amplifier gain is fixed. If your output would exceed the rated output, then your amplifier will produce either a very distorted signal, or a lot of smoke. \$\endgroup\$
    – Juancho
    Commented Oct 20, 2014 at 15:52
  • \$\begingroup\$ is that mean total gain of 3 elements system will not be 180 db ? \$\endgroup\$
    – man abduo
    Commented Oct 20, 2014 at 19:16

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