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 Note: Hyperlinks all around the Internet pointing
to Hittite's infamous
Mixer Spurious Product Calculator broke suddenly when
Analog Devices swallowed
them up in 2014. For a while you could find it as
the ADI Mixer-Spur
Graphical Representation tool on the ADI website, but now it is gone, too, and
even the
WaybackMachine does not have a capture of it.
Marki Microwave now has a much nicer
Spur Calculator.
Hittite's online JavaScript app for finding mixer spurious products has been around
for many years, but in case you have forgotten about it or have never seen it, now is
a good time to bookmark the page. It uses a format pioneered by Collins Radio back in
the middle of the last century that plots the RF/LO and IF/LO harmonics as straight lines,
and then draws a rectangle within them that represents the limits of the output frequency
band. Any spurious product lines that pass through the rectangle are inband at the output,
and hence cannot be filtered out after the fact. I dubbed the chart a "Spur Web"
in my DOS-based RF Workbench program back around 1990. It was, I believe, the first time
that chart format had ever been implemented in software with a graphical user interface.
Posted November 12, 2012 (update April 2, 2021)
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