AnsweredAssumed Answered

ADF4007 (eval board) as phase detector and PLL

Question asked by zwarren on Nov 5, 2014
Latest reply on Nov 6, 2014 by zwarren

I have an eval ADF4007 which I want to use to phase lock two lasers together. I'm testing it before getting to that feedback part, and I'm having an issue with error output from the CP/phase detector:

 

Capture.PNG

Setup:  RF synthesizer for 6.8 MHz and another RF synthesizer for 106.8 MHz.  Vtune out is going to an oscilloscope.  Muxout going to a spectrum analyzer just to check.  Also M2 and M1 are set to 1 and 0, respecticvely for "active" CP and Muxout at N divider output with a PFD polarity of +ve.

 

Questions:

 

  • This PLL is supposed to be comparing the REFin with the divided RFin, right?

 

  • Is the Phase detector output the Vtune output of the board?

 

  • When I change the phase of the 6.8 GHz input, shouldn't I be getting some change at the Vtune output?  It is always at 0, regardless of what I change in the input signals.

 

Thank you,

Zack

Outcomes