replacement for Varactor diode
you can consider step recovery diode which has very similar characteristic. if you need cheap cost product, the capacitance will be high, normally
Do you have a number in your mind?. because change ratio is the main issue I need 70 pf at 1v and only 7 pf at 10-12 volt
you can refer the product from Macom,the GaAs diode has high Q.
The other from TOKO,philiph,toshiba...
I need some thing cheaper. what about step recovery diode how much change rate will be availble?
Najf: check out
http://www.metelics.com/spiceStepRecovery.htm
the diode has very low capacitance. (but it is in die form)
for lower cost SRD, check out
http://www.chipdocs.com/pndecoder/da...M/MA44769.html
What is a step recovery diode?
The doping profile in this diode is optimized for the removal of the stored charge to end in a rapid dq/dt. Stored charge is generated in forward bias and removed in reverse bias. This sudden stopping of the reverse current causes a current waveform with large amplitude levels of the higher harmonics. This diode is used in frequency multipliers commonly called comb generators from the graphical shape of the graph of the frequency spectrum.