Rough Guide For The Noise Figure Test System Configuration - Keysight Technologies N9040B UXA Manual

Making Noise Figure Measurements
Using the U7227-Series USB Preamplifiers in Noise Figure Measurements

Rough Guide for the Noise Figure Test System Configuration

To configure the test system for accurate noise figure measurements, the first
priority is to make the instrument noise figure (USB preamplifier + signal
analyzer) as low as possible. To reduce the instrument noise figure, the USB
preamplifier and internal preamplifier should be used whenever possible. If an
overload or compression exists in the test system, removing or turning off the
preamplifier (USB preamplifier or internal preamplifier) or adding internal
attenuation can eliminate the problem. On the signal analyzer,
— To turn on/off the internal preamplifier, press AMPTD, Signal Path tab,
— To set the internal attenuator, press AMPTD, Attenuation tab, and set the
Figure 2-16
figure and gain) of different system configurations for different frequency
ranges up to 26.5 GHz. The X-axis is for the DUT noise figure, the Y-axis is for
DUT gain. This rough guide is based on the noise power calculation before the
non-linear components. For more details about noise power calculation in
different stages of the test system, refer to
Different Stages of the Noise Figure Measurement System" on page
Before using
configuration, you need to pay attenuation to the following points:
— The DUT reference bandwidth used to calculate the noise power is 3.59
— The noise figure and gain for the U7227C USB Preamplifier are used in the
— A 6 dB ENR noise source is used in the calculation. If you are using a noise
— For different instruments and for a wide frequency range, the data for the
42
Internal Preamp, On/Off.
attenuation.
and Figure 2-17
Figure 2-16
GHz, which is the worst case for the lower band (10 MHz to 3.6 GHz). To
maintain consistency between the lower band and higher band, the same
DUT reference bandwidth is used in the calculation for frequency ranges
above 3.6 GHz. Then the reference bandwidths (Ref BW) for both below 3.6
GHz and above 3.6 GHz are both 3.59 GHz.
If the DUT has a narrower bandwidth, the DUT characteristics can be
increased accordingly. For example, if the DUT has a bandwidth of 100
MHz, the supported DUT gain can be increased by a factor of
9
10 × log ( 3.59 10 × ⁄ 100 10 ×
calculation. If you are using the U7227A or U7227F, the supported DUT
characteristics should be different.
source with higher ENR, the supported DUT gain will be lower.
USB preamplifier and the X-Series signal analyzer differs considerably, the
most precise data is used in most cases.
show the supported DUT characteristics (noise
"Calculating the Noise Power into
and Figure 2-17 to find a proper test system
6
, that is by 15.6 dB.
)
N9069C Noise Figure Measurement Guide
85.