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AD9361 PLL synthesizer and LO harmonic filtering

Question asked by arvabj on Apr 19, 2016
Latest reply on Apr 22, 2016 by tlili

Hello,

 

I am interested in using AD9361 for low frequency RF ranges 150-200 MHz. In my experience with discrete, wideband PLL synthesizers covering few 10's of MHz up to 6GHz, the LO harmonic levels in the lower frequencies are high.The PLL LO output cannot be used  directly to drive an IQ mixer without LO harmonic rejection  filtering. The image rejection is pretty bad without a filtered LO signal. With a fully integrated solution, does the AD9361 implement such harmonic rejection filtering for the programmable RF/LO synthesizers ? I do see Tx quadrature calibration features for the AD9361 to achieve optimal sideband and LO leakage levels. Is this calibration sufficient to ensure good performance in low frequencies going down to 70MHz ?

 

The same question goes for the Front-end Baluns. What is the drawback of using a wideband  TCM1-63AX+  type of balun and working across the entire 70MHz to 6GHz range ? Are narrow-band baluns needed/ recommended in lower frequency ranges ?


Your feedback is highly appreciated. Thanks,

AB

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