Atek HP 8753D, User Manual, Page: 418 / 677

Filtering
Harmonics , linearity , and spurious signals also introduce errors that are not removed by
frequency response calibration. These errors are smaller with a narrowband detection scheme ,
but they may still interfere with your measurements . Y ou should lter the IF signal to reduce
these errors as much as possible .
Correct ltering between the mixer's IF port and the receiver's input port can eliminate
unwanted mixing and leakage signals from entering the analyzer's receiver . Figure 6-89 shows
a plot of mixer conversion loss when proper IF ltering was neglected.
Figure 6-89.
Example of Conversion Loss versus Output Frequency Without Correct
IF Signal P ath Filtering
Figure 6-90 shows the same mixer's conversion loss with the addition of a low pass lter at the
mixer's IF port.
Figure 6-90.
Example of Conversion Loss versus Output Frequency With Correct IF
Signal P ath Filtering and Attenuation at all Mixer P orts
Filtering is required in both xed and broadband measurements , but you can implement it more
easily in the xed situation. Therefore , when conguring broad-band (swept) measurements ,
you may need to trade some measurement bandwidth for the ability to more selectively lter
signals entering the analyzer's receiver .
6-152 Application and Operation Concepts