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Design >> RF Design >> Question about varactor (VCO design)
https://designers-guide.org/forum/YaBB.pl?num=1403711647

Message started by azw on Jun 25^th, 2014, 8:54am

Title: Question about varactor (VCO design)
Post by azw on Jun 25^th, 2014, 8:54am

Hi,

I’m reading materials about VCO design for reference, and in one of them there is something I can’t understand:

“Substituting this result gives Cv = 675fF. Because the varactor is in series with a 5pF AC coupling MIM capacitor, its actual value should be increased to about 790fF.”

Why exactly we should increase the value of Cv?

Thank you!

Title: Re: Question about varactor (VCO design)
Post by raja.cedt on Jun 25^th, 2014, 9:12am

Generally in Ac coupled varactors bottom plate will be connected to varactor side rather inductor side.May be MOM bottom plate cap, which is coming in // with actual cap..

Thanks,
Raj.