Calculating The Noise Power Into Different Stages Of The Noise Figure Measurement System - Keysight Technologies N9040B UXA Manual

Measurement Related Tasks and Concepts
Calculating the Noise Power into Different Stages of the Noise Figure Measurement
System
Calculating the Noise Power into Different Stages of the Noise
Figure Measurement System
Figure 3-8
noise figure measurement. The blocks with dotted lines indicate that you can
choose whether to use them or not. The non-linear components in the signal
path include the USB Preamplifier, the internal preamplifier and the input
mixer. The input noise power of these components should not exceed the
maximum value for the linear range.
Figure 3-8 Blocks in the Signal Path of the Noise Signal in the Noise Figure Measurement
To calculate the noise power in different stages,
Equation 3-2 P
noise
in which,
— The unit of
— -174 dBm/Hz is the thermal noise per hertz calculated from
— BW is the bandwidth of the DUT, for most cases. The unit is Hz. If you are
—
— F is the noise figure in linear terms of a part of the test system, which is from
—
N9069C Noise Figure Measurement Guide
show the possible blocks in the signal path of the noise signal in the
174 10 log
×
= – +
is dBm.
P
noise
going to calculate the noise power of the input mixer for frequency ranges
higher than 3.6 GHz, BW is the bandwidth of the preselector, which is
usually below 80 MHz.
is the excess noise ratio of the noise source. Normally, the ENR of a
ENR
linear
noise source is given in dB.
ENR 10
( ⁄
ENR 10
dB
=
linear
the DUT input to the input point of the noise power under calculation. For
example, if you are calculating the noise power of the input mixer for
frequency ranges below 3.6 GHz, the F includes the noise figure for the
combination of DUT, USB Preamp, internal attenuator, internal preamp.
is the gain of a part of the test system, which is exactly the same part
Gain
dB
as that is used in F calculation. For example. if you are calculating the noise
power of the input mixer for frequency ranges below 3.6 GHz, use the
following equation.
Equation 3-2
BW 10 log
( ) × (
+
10 10
)
is used:
ENR F Gain
)
+ +
linear dB
.
kT
0
85