Help with VCO design

Hi,

I have a project to design a VCO which i have difficulties with. Could
someone please help me out? I have the following specifications:
band: 1430 to 2230 MHz
comparison frequency: 7.8125 kHz
VCO output power: 10 mW

I don't know how to find the value of the needed varactors, the rest of the elements and the s-parameters.

A help or a direction would be much appreciated!

Looks like a home work question.

The Ctun(s) are in series. Ctun(totoal)=???Ctun1 ???Ctun2 (you find the formulas)
Cp and Ctun(total) are in parallel. C=Cp+Ctun(total)
You know or can find the resonance formula. F=???CL

Find what diodes are available. Look in a catalog or look on the internet.

At high frequency the frequency is mostly L and Cp because Ctun(s) is small.
At low frequency the frequency is more related to Ctun because Ctun in large.

I use a spread sheet and put the formulas in and play with values.

Your ratio of frequency is 1.55 F(Max/Min) So choose a diode that can do more than that.
Example BB814 has a cap value of 2.25 to 22.7pF. This will leave your Cp value very small. Should work.

Show your work and post back when you are done.

Thank you so very much for the help ronsimpson ! Your answer is really helpful