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Data Clock Harmonic Spures at AD9361 Tx output

Question asked by kfirkam on Nov 9, 2015
Latest reply on Nov 9, 2015 by tlili



I am experiancing some issues with high harmonic spurs which seems to be sourced from my Data clock = 30.72MHz. (noticed on the Balune output stage at -80...-90dBm power level). Its harmonic falls directly on my Tx operation band and increased in my RF FE due to a PA.
I'm trying to debuge this issue and I would appriciate your assistance in that.

  1. I am using the built-in FIR filters from Matlab Application: "AD9361 Filter Design Wizard Version 2015_R1"
  2. In my design- Tx1A is sourced from LDO: ADP1755ACPZ
  3. On TX1A/1B I have RF Choks and also 3 bypass cap of 1uF/10nF/100pF
  4. A Balune 50/50 : B0322J5050AHF Anaren-Xinger family type.
  5. A WideBand LNA 50-4000 from RFMD


Can you please point out if there is any approach of reducing the Data Clock spurs which output from the Catalina device?