I have been reviewing my old text books on semi conductor circuit approximations to refresh my memory. I have run in to a problem at the end of a chapter that I can not figure out.

If I have a 100 microHenry inductor in parallel with a varcator, what range of capicitance does the varactor need to have to tune the am radio band 535 to 1605 kHz?
Should I use the resonant frequency formula and solve for C at 535 and 1605kHz?

Any help is appreciated.

 

Yes, the variactor is treated as a variable capacitor, no more. The specs on the diode define whether it will achieve the needed capacitance.

 

Hello,

For calculation of the resonance frequency you can take a look at this page of the AAC eBook.

http://www.allaboutcircuits.com/vol_2/chpt_6/2.html

For information on varicap diodes take a look at this page of EDUCYPEDIA.

http://www.educypedia.be/electronics/composemiconductordiode.htm

Greetings,
Bertus