Measuring 75 Ohm Devices - Keysight Technologies N4374B User Manual

Measurement Concepts

Measuring 75 Ohm devices

52
Since the system impedance of the LCA system is 50 Ohm, some
additional steps are required to measure devices with 75 Ohm
impedance.
The system expects a valid 50W electronic calibration to the end
of the RF cables is available and active.
On the LCA user interface you need to check the 75 Ohm
checkbox. This checkbox is only enabled when the "RF Path
Deembedding" is also enabled. The LCA assumes that your
device is connected with minimum loss pads for impedance
conversion.
In the "RF Path Deembedding" box you need to specify the
deembedding data for the minimum loss pads.
Internally the LCA sets the reference impedance of the network
analyzer to 75 Ohm, scales the receiver or transmitter
calibration data to a 75 Ohm environment and adds the
minimum loss pad data to the deembedding data for the
network analyzer. This extends the calibration reference plain
to the 75W DUT interface.
The files delivered with the LCA are typical data for the
Keysight 11852B minimum loss pads. By default, they are
located on the network analyzer at
D:\Keysight\Data\AdapterCharacterization\11852B.s2p
If you want to use data for your individual pads, measure them
using the adapter characterization utilities on your PNA or ENA
network analyzer. On the PNA Series Network analyser the
characterization can be performed using mechanical or
electronic calibration kits. On the ENA Series network analyzer
this procedure requires 75Ohm N-type mechanical calibration
standards e.g. 85036B/E.
If not already installed, the adapter characterization VBA macro
for the ENA can be downloaded from
http://www.keysight.com/main/editorial.jspx?
cc=US&lc=eng&ckey=85082&nid=-11143.0.00&id=85082
The adapter characterization procedure is described in detail in
an application note.
Keysight N4374B Lightwave Component Analyzer, User's Guide