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EV-RADAR-MMIC2 spurious

Question asked by luigimaggi on Dec 22, 2017
Latest reply on Jan 4, 2018 by Xueru.Ding

Hi there,


I'm an issue with the EV-RADAR-MMIC2 board. I set up the evaluation board to work with an external reference.

The reference of 100MHz sinwave OCXO oscillator (0 dBm) is used to generate a 24GHz signal tone.

I've programmed the boards with EV-RADAR-MMIC2 control software so that the PLL ADF4159 works in integer mode.

As you can see in the attached figures the power spectrum output signal with external reference shows several spurious close to carrier signal at offset frequencies of 500 Hz, 1KHz, 1.5KHz and so on.

Such spurious, however, doesn't occur with internal or external TXCO oscillator, even if the phase noise is never better then 75 dBc/Hz (the figure attached displays the spectrum signal with external TCXO signal reference at 100MHz and 0 dBm power).

I've tried to set the charge pump and negative bleed current but I've not had any improvements.


Thank you,