Hi,

FYI there is an error in the white paper "Modeling varactors" eqts (21) states that q(v)=C0*v+C1*v1*ln(cosh((v-v0)/v1)). There is a missing term because clearly if v=0 there is still a charge in the capacitor which is physically wrong the correct integral is q(v) =c0*v+v1*c1*( ln(cosh((v-v0)/v1)) - ln(cosh(v0/v1)) ).
The error does not appear if you are interested in the current because of the derivative, but the charge in the capacitor is wrong.

City