Concepts and Features
R&S
®
ZNB/ZNBT
205
User Manual 1173.9163.02 ─ 38
●
The mixer mode can be used to test important performance parameters of RF mix-
ers such as frequency ranges, conversion loss, compression, and isolation.
Two-Stage Mixer Measurements
The scalar mixer measurement is also suited for measuring a system of two mixers
with frequency multipliers at their RF and LO inputs. The RF and LO input frequencies
of the first mixer are both multiplied by an integer fraction; the converted output signal
f
int
is fed to the second mixer, together with the multiplied second LO signal. The ana-
lyzer measures the output signal of the second mixer at its IF input port. The general
test setup is shown below; the mixer system under test (MUT) is enclosed in a blue
rectangle.
The figure above also shows the possible output frequencies of the two mixers. The
actual values of f
int
and f
IF
depend on the RF and LO frequencies and of the measured
conversion (lower sideband or upper sideband with up- or down-conversion). The ana-
lyzer automatically calculates all frequencies and sets its receiver according to the set-
tings made.
A test setup with two mixers requires 3 independent source ports plus one receive port.
A R&S
ZNB/ZNBT with two internal sources (see
Chapter 4.7.7, "Internal Second
on page 212) requires one external generator, all other R&S
ZNB require two
external generators.
A standard mixer measurement with a single mixer stage and no frequency multipliers
corresponds to the figure above with the second mixer and LO 2 omitted and m
1
= n
1
=
m
2
= n
2
= 1.
Mixer Diagrams
The mixer signal diagrams show the parameters of the mixer input signals (RF, LO)
and of the mixing product (IF signal, output).
●
The RF signal is the stimulus signal that the analyzer generates with the current
channel settings. After a reset the frequency and power of the RF signal is as
defined in the Channel – Stimulus menu. The RF signal parameters can be
changed in the "Power" and "Frequencies" dialogs.
Optional Extensions and Accessories
