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ADF4159 EVA-board Fast ramp mode setting issue

Question asked by Newpp on Apr 19, 2017
Latest reply on Jun 1, 2017 by dyoung1

I am doing some research about fmcw fast ramp on the ADF4159 EVA-board.

Photo 1 is the PLL setting, Photo 2 is the tuning waveform.

 

ADF4159 setting:

ramp mode: continuous triangular 

fast ramp: enabled

the total frequency change of the up and down ramps are the same.

The differences are: up and down ramp steps

                                 up and down time of ramp

                                 frequency deviation per step

Question: how come I can't see the 16 steps down ramp? It is about half time of the up ramp, should be obvious.

By the way, when I pulse TXdata, I do see the change of frequency of 64 steps up ramp, 16 steps down ramp.

 

Waiting for the help! Thanks!

 

 

Big Update: In photo 3 I found the gap between up ramp. Blue is the Clk divider output, which shows each step.

I zoom in to the down ramp (photo4), I actually see the steps. Is that right?

However, the down ramp time is not what I program. How to explain it?

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