AnsweredAssumed Answered

Programming ADF4106

Question asked by sinan.onat on Nov 3, 2017
Latest reply on Nov 24, 2017 by sinan.onat


I can not get my PLL work, I believe it is because of not correctly programming ADF4106, please confirm the below words are correct for initiating and setting 1030 MHz. Here are the words I sent for initial setting after power up:






Here, I use a 40 MHz reference signal. I would like to observe the MOSI signal outputted through MISO (muxout) pin.

1) Yet, I could not achieve the 1030 MHz signal outputted. Instead, I achieve the highest VCO frequency available. Therefore it seems that the charge pump of my PLL does not lead the returned signal from VCO. I attached my PLL circuitry for reference. I use THS4031MFKB (OpAmp) from TI, which has a positive bias of +5V, negative bias of -3.3V and reference voltage of 1.4V. What do I do wrong?


2) Assuming that I will be achieving the 1030 MHz signal (locked), I think that I have to send 0x00201D word to set the frequency 1031 MHz, and wait for it is being locked. For returning back to 1030 MHz (I am not interested in any fast locking or jumping to previous frequency privileges), shall I send again 0x002019?


3) In my PCB, there is not any sequentially turn-on for bias. All my parts (PFD, OpAmp, VCO etc.) get energized at the same time. I hope it is not a problem, I believe it is not, please also verify that.


4) Lastly, maybe I shall be setting phase detector polarity to negative, although the default setting is positive. I also need a direction (or confirmation) on that too.


Thank you in advance for assisting me in above four items.


Sinan ONAT