Noise Measurement Group Operation (Option 029); A52 Test Port 1 Option 029 Switch; A53 Test Port 2 Option 029 Switch; A54 Test Port 2 Option 029 Bridge - Keysight N5241A Service Manual

Theory of Operation

Noise Measurement Group Operation (Option 029)

Noise Measurement Group Operation (Option 029)
The noise measurement group measures the noise figure up to 26.5 GHz.
Figure 5-8 on page 5-30
measurement group. Although the 4-port configuration is shown, the 2-port
configuration is very similar. Refer to the detailed block diagrams at the end of
Chapter 4
In this section the following assemblies are described:
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A52 Test Port 1 Option 029 Switch

The A52 bypass switch is placed in the Port 1 source path, allowing the source
signal to be switched in and out of the path if needed when an external
Electronic Calibration (ECal) module is used in the test configuration. An
external ECal module is placed in the test configuration between Port 1
SOURCE OUT and Port 1 CPLR THRU as an impedance tuner where there
would normally be a front panel jumper. The ECal module is not part of the
option 029 hardware but is required as an impedance tuner for a fully vector
source corrected noise figure measurement.

A53 Test Port 2 Option 029 Switch

The A53 bypass switch is placed in the Port 2 source path, allowing switching
between normal test mode configuration and noise figure measurement mode.

A54 Test Port 2 Option 029 Bridge

The A54 bridge is placed in the Port 2 source path. When the PNA-X is
switched into noise figure measurement mode, the noise incident signal from
the DUT passes through the A54 bridge before being sent to the A55 noise
downconverter. The A54 bridge also allows the source incident signal from A5
to pass through to Test Port 2 where the S-parameters and conversion gain
measurements can be done without any extra mechanical switching.

A55 Noise Downconverter

The A55 noise downconverter board contains an input low noise amplifier
(LNA), an RF filter bank, an LO filter bank, and a mixer. For 3 – 26.5 GHz
signals, the LNA provides the necessary gain, to enable measurements on low
noise and low gain devices. The signals are routed through the RF filter bank
where the noise signal is filtered for third harmonic conversion rejection.
5-28
if necessary.
A52 Test Port 1 Option 029 Switch
A53 Test Port 2 Option 029 Switch
A54 Test Port 2 Option 029 Bridge
A55 Noise Downconverter
A7 Noise Receiver Board
is a simplified block diagram of the noise
Keysight N5241A/42A/49A Service Guide