Keysight Technologies CXA N9000B, Manual

Page: 76 / 88

76 N9069C Noise Figure Measurement Guide
Measurement Related Tasks and Concepts
Setting the Signal Analyzer to Make a Measurement
To select the input attenuation calibration range, press MEAS SETUP , Cal
Setup tab, User Cal and select the attenuation range you want using the
Min Atten and Max Atten selections. Use Table 3-4 on page 75 as a guide to
what range you require.
Setting the Input Attenuation used for Measurement
The attenuators cannot autorange. When making a measurement you must
manually set the input attenuation to avoid overdriving the analyzer.
To set the input attenuation, press
AMPTD, Attenuation Tab and enter the
desired measurement attenuation using the numeric keys.
3.6 GHz to
26.5 GHz
c
(Analyzers with
microwave
preamplifiers)
0 dB –31 dBm A wide bandwidth DUT with NF = 5 dB and Gain <39 dB, or NF
= 15 dB and Gain < 32 dB
4 dB –27 dBm Gains 4 dB higher than the 0 dB attenuation case
8 dB –23 dBm Gains 8 dB higher than the 0 dB attenuation case
12 dB –19 dBm Gains 12 dB higher than the 0 dB attenuation case
3.6 GHz to
26.5 GHz
c
(Analyzers
without
preamplifiers)
0 dB –14 dBm A DUT with 80 MHz bandwidth, NF=10 dB and Gain up to 63
dB can be accommodated when using a 17 dB ENR noise
source. With wider bandwidths, even more output noise can be
accommodated. When no preamplifier is used in the analyzer,
the input noise outside the preselector bandwidth (nominally
40 to 80 MHz) gets reflected without causing nonlinearities in
the analyzer input stages.
a. The figures given in this table assume a 5 dB ENR noise source.
b. If the DUT has a narrower bandwidth than the 10 MHz to 3.6 GHz specified here, the DUT characteristics can be
increased accordingly for bandwidths down to 12 MHz. For example, if the DUT has a bandwidth of 100 MHz, the
DUT characteristics can be increased by a factor of 10 x log(3.59 x 109/100 x 106), that is by 15.6 dB. In this
example with an attenuation setting of 0 dB, the Gain of a DUT with a 15 dB noise figure can be increased from 37
dB to 52.6 dB. For bandwidths narrower than 12 MHz, the allowable power does not increase further than it does
at 12 MHz.
c. In the 3.6 – 26.5 GHz frequency range, the situation is considerably more complicated than in the low band case
and footnote. The ability of the preamp to handle large signals is poorest at 3.6 GHz, the frequency for which the
example in the table applies. The ability to handle large signals increases linearly with frequency, increasing about
11 dB at 26 GHz. Also, the allowable gain of the DUT does still increase as its bandwidth decreases, but only down
to bandwidths of about 70 MHz.
Table 3-4 Power Detection and Ranging on X-Series Signal Analyzers
Frequency Attenuation
Setting
Maximum
Input Power
for High
Accuracy
Approximate DUT Characteristics
a
The measurement input attenuation must be within the calibrated
attenuation range.