Keysight Technologies CXA N9000B, Manual

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38 N9069C Noise Figure Measurement Guide
Making Noise Figure Measurements
Using the U7227-Series USB Preamplifiers in Noise Figure Measurements
Initial Connection to the Signal Analyzer
The U7227-Series USB Preamplifier is powered via a USB connection from the
signal analyzer. To connect it to the analyzer, follow the steps below.
1. Connect the Output port of the USB preamplifier to the RF Input port of
the signal analyzer.
2. Connect the USB port (Type-A) of the USB preamplifier to the USB port
(Type-A) of the signal analyzer either in the front panel or in the rear panel
using a USB cable. You can “hot plug” the USB preamplifier into the
analyzer’s USB port at any time.
Figure 2-12 shows the U7227-Series USB Preamplifier connection in the two
stages of the noise figure measurement. While the USB preamplifier is plugged
into one of the analyzer’s USB ports, the analyzer will consider it to be in the
RF input signal path and will apply the gain settings and other calibration data
of the USB preamplifier to the measurements. Therefore, adding preamplifier
correction data is not necessary.
Figure 2-12 U7227-Series USB Preamplifier and Analyzer Connection in the Two Stages of
Noise Figure Measurement
In the noise figure measurement application, the signal analyzer will respond in
the following manner when the USB cable of the U7227-Series USB
Preamplifier is plugged into one of the analyzer’s ports:
Before connecting a signal to the input port of the U7227-Series USB
Preamplifier, make sure the USB preamplifier can safely accept the signal
level provided. The signal level limits are marked next to the Input
connectors of the USB preamplifier.
The USB connections of the U7227-Series USB Preamplifier and the keyboard to
the signal analyzer must be separated from each other; for example, the USB
preamplifier connects through the front panel while the keyboard connects
through the back panel.