Post subject: Noise from a Class C Amplifier Posted:
Fri Jan 27, 2006 10:37 am
This might be a
simple question, but I need some assistance. I am looking at the
noise generated by a Class C amplifier (to keep things simple, lets
assume it is has a 10 watt amplifier) and how to measure it.
Also I would like to know if anyone has some suggestions about
how to analyze the noise (instead of measuring it, can I perform
some calculations and get an approximate answer?)
has anyone tried to simulate the noise from a Class C amplifier?
Any information will be appreciated - websites, magazine articles,
Post subject: Posted: Sun Jan 29, 2006 11:54 am
Joined: Mon Jun 27, 2005 2:02 pm
You can measure the
output noise of the PA by using Spectrum Analyzer. You first have
to measure the output noise when the PA is off, this result will
be used as reference point, you have to know the temperature at
which it was measured. Then turn on the PA and notice that the noise
floor is increased. Make these measurements at the same RBW.
The difference between the noise floors at both cases is the
gain of the noise + PA´s Noise Figure. Of course that the noise
is also dependent on the BW of operation (RBW of the SA in this
case) and the temperature according to: Pn=kTB
calculation, you can deduce the self-contribution of the PA to the