It appears as thought the low pass filters in PSpice have a rather long phase delay. Is this characteristic exagerated in PSpice or is that what I could typically see in the real world? I'm trying to implement a Costas loop, and I just cant get my vco to catch up with my RF. It appears as though the delays through the filters are too long.
Anyone every do anything like a costas loop in PSice before?
What low pass filters are you speaking of?
Are you aware that PLL's need a lead-lag filter? A pure low pass will be slo-o-o-ow to lock, or may not lock at all.
I just remembered this model....
Rin in 0 1G Rtable table 0 1G
Etable table 0 Value {Table(V(in),Vmin,-1,Vmax,1)}
Esin out 0
+Value {sin(6.28318*(Fcenter*time+Frange*SDT(V(table)))+phase*(3.14159/180))}..ends
...Jim Thompson
A PLL will lock without a filter at all.
If a filter is used it needs to be a lag-lead otherwise the loop will be unstable, not because it might be slow without a lead.
Kevin Aylward snipped-for-privacy@anasoft.co.uk
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