AnsweredAssumed Answered

Regarding Phase noise of ADF5355 PLL

Question asked by Narendra_S on Dec 30, 2017

Hi guys,

I am using the ADF5355 Evaluation board.

I need to generate 13.3 GHz output frequency (using doubler)

 

I have 2 OCXOs

1.

Using 10MHz Ref: single ended mode--- the OCXO phase noise

parameter is -157 @ 100Hz, -165 @ 1KHz and -170 @ 10KHz

I have kept my PFD @ 10MHz.

I have tweaked the loop filter.

The best phase noise I am getting at 13.3 GHz is

-76 @ 100 Hz, -84 @ 1KHz and -85 @ 10 KHz....  How do I improve this phase noise value.

I have attached the plot for reference.

 

2.

Using 100MHz Ref: single ended mode--- the OCXO phase noise

parameter is -100 @ 100Hz, -115 @ 1KHz and -125@ 10KHz

I have kept my PFD @ 50MHz. (using divider)

I have tweaked the loop filter.

The best phase noise I am getting at 13.3 GHz is

-76 @ 100 Hz, -89 @ 1KHz and -95 @ 10 KHz....  How do I improve this phase noise value.

I have attached the plot for reference.

 

3.

Using 100MHz Ref: single ended mode--- the OCXO phase noise

parameter is -100 @ 100Hz, -115 @ 1KHz and -125@ 10KHz

I have kept my PFD @ 100MHz.

I have tweaked the loop filter.

The best phase noise I am getting at 13.3 GHz is

-76 @ 100 Hz, -86 @ 1KHz and -92 @ 10 KHz....  How do I improve this phase noise value.

I have attached the plot for reference.

In addition the spurs are more in this PFD. And phase noise has not increased as expected.

Please advise what is the best PFD and why am I not achieving good phase noise and spurs at 100 MHz PFD.

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