HI,

I am about to finish my 80 MHz Quartz Crystal VCO, but I am not confident on Jitter's results. Please try to answer these questions, as fast as you can, as I have the tape-out in August of the full PLL:

1 - For the VCO circuits (autonomous circuits), which jitter measurement type should I use: FM or PM (I am using FM)? I think we should use FM for the autonomous circuits and PM for the driven ones. Is this correct ?

2 - Sweep range: should I configure it till fo, fo/2, 2fo. I have no idea on this.

3 - Integration limits: I am using 1Hz to fo/2 (40 MHz). Is this correct ? How this relates with the sweep range ?

4 - How should I plot phase noise ? Under pnoise jitter or pnoise? The results are quite different.

5 - Which is the most suitable jitter for VCO's Jc or Jcc ?

6 - I have read the Ken's papers but, if I am not mistaken, he says that the great majority of the phase noise should be close to the carrier. However, integrating from the carrier till the corner frequency, I get a lower contribution than for big offsets. Can you please comment on this ?

Thanks very much to all.

Best regards,
Pedro