StepByStep Overview of SpurKiller Technique

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Step-By-Step Overview of SpurKiller Technique
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SpurKiller Technology
Direct Digital Synthesis is a sampled system...
In sampled systems, spurs are a fact of life
Typical Narrow Band spectrum with spurs
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SpurKiller Technology

• Spurs ARE...
• Predictable
• Frequencies at which spurs appear are simple
  functions of the sampling rate and the programmed
  output frequency

BUT

• Fairly repeatable
• Frequencies are constant for any FTW
• Phase of each spur does not change
• Amplitude does change somewhat across
  temp/process/voltage

SO
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SpurKiller Technology - Narrowband
Problematic spurs in the output spectrum can be
cornered and attacked using our patented
SpurKiller technology
SpurKiller technology utilizes additional
internal DDS channel(s) to knock selected spurs
down to the noise floor
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Wideband spur example
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Wideband spur knocked down
14 dB improvement wideband SFDR
Noise floor rises a little
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SpurKiller Technology
Step 1 Find your largest spur
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SpurKiller Technology
Step 2 Program SpurKiller channel to a frequency
slightly higher than that spur
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SpurKiller Technology
Step 3 Program SpurKiller channel amplitude to
match spur amplitude
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SpurKiller Technology
Step 4 Program SpurKiller channel to match spur
frequency
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SpurKiller Technology
Step 5 Adjust phase of SpurKiller channel until
the spur is minimized
Note The Spurkiller function on the AD9912
automatically performs some of the steps