Hi.(adsbygoogle = window.adsbygoogle || []).push({});

I know [itex]G_P (dB) = 10log(G_P)[/itex] and [itex]G_V (dB) = 20log(G_V)[/itex] and [itex]G_I (dB) = 20log(G_I)[/itex].

I also know that [itex]G_P (dB) = G_V (dB) + G_I (dB)[/itex].

So, if I have a common base amplifier whose current gain is [itex]G_I (dB) = 0[/itex], then [itex]G_P (dB) = G_V(dB)[/itex].

Suppose

[itex]G_V (dB) = 20 dB[/itex]. So [itex]G_V = 10^{20/20} = 10[/itex]

[itex]G_I (dB) = 0 dB[/itex]. So [itex]G_I = 10^{0/20} = 1[/itex]

As I've written above, then [itex]G_P (dB)= G_V (dB) = 20 dB[/itex]. So [itex]G_P = 10^{20/10} = 100[/itex].

But, in linear scale (not in dB), [itex]G_P = G_V\cdot G_I[/itex], so [itex]G_P = 10\cdot 1 = 10[/itex], which is not [itex]100[/itex].

What's wrong?

Thanks!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Power, voltage and current gain

Loading...

**Physics Forums | Science Articles, Homework Help, Discussion**