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AD9625 with free-running VCO

Question asked by bsalz@work on Aug 8, 2017
Latest reply on Aug 8, 2017 by Clarence.Mayott

Hi there,


I was curious about recommended clocking methods for the AD9625. Looking at the eval board, there seem to be three options:


  • AD9525 PLL/VCO 
  • Avago wideband VCO
  • Qorvo narrowband VCO


I am asking if there is any way to calculate the SNR degradation due to sampling jitter when using one of the open-loop VCOs. For closed-loop PLLs it's relatively straightforward to define a phase noise BW and integrate over that, but the phase noise profile of an open-loop VCO is dramatically different. Any recommendations?