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An amplifier
If a source is not able to provide a sufficient output level, or if additional
isolation is needed at the output, it may be necessary to insert a low
phase-noise RF amplifier at the output of the source.
Note, however, that the noise of the inserted amplifier is also summed into the
measured noise level along with the noise of the source.
The Agilent N5507A Option K22 dual RF amplifier was designed specifically
for this purpose. This instrument is the preferred solution for tests requiring
an external amplifier.
Use the following equation to estimate what the measurement noise floor is as
a result of the added noise of an inserted amplifier:
example.
L(f) out = –174 dB + Amplifier Noise Figure – Power into Amplifier – 3dB
L
L
Figure 81 Measurement noise floor as a result of an added attenuator
Agilent E5505A User's Guide
Amplifier
P IN = +7 dBm
Noise figure = 7.5 dB
( f ) = -174 dBm + 7.5dB - (+7 dBm) - 3 dB
( f ) = -176.5 dBc/Hz
Absolute Measurement Fundamentals
Figure 81
shows an
E5505a_noise_floor_atten
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