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Mixer Parameters
That
You Can Measure
Pg6
140d
Figure 6-88.
Mixer
hrameters
w
Transmission characteristics include conversion loss, conversion compression, group delay,
and RF feedthru.
n
Reflection characteristics include return loss,
SWR
and complex impedance.
n
Characteristics of the signal at the output port include the output power, the spurious or
harmonic content of the signal, and intermodulation distortion.
n
Other parameters of concern are isolation terms, including
LC
to RF isolation and
Lo
to IF
isolation.
Accuracy Considerations
In mixer transmission measurements, you have RF and
LO
inputs and an IF output. Also
emanating from the IF port are several other mlxing products of the RF
and LO signals.
In
mixer reflection measurements, leakage signals from one mixer port propagate and appear
at the other two mixer ports. These unwanted mixing products or leakage signals can cause
distortion by mixing with a harmonic of the analyzer’s
llrst
down-conversion stage.
‘lb
ensure
that measurement accuracy is not degraded, you must
filter
certain frequencies or avoid them
by frequency selection. If you place attenuators at all mixer ports, you can reduce mismatch
uncertainties.
6-168
Application and Operation Concepts