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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> Error in Modeling varactors paper https://designers-guide.org/forum/YaBB.pl?num=1103710476 Message started by City on Dec 22nd, 2004, 2:14am |
Title: Error in Modeling varactors paper Post by City on Dec 22nd, 2004, 2:14am 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 |
Title: Re: Error in Modeling varactors paper Post by Mighty Mouse on Dec 22nd, 2004, 9:14am City, There is no reason why the charge of a nonlinear capacitor must be zero when the voltage across it is zero. Furthermore, the absolute charge on a capacitor is of no consequence, only the change of charge is important. So the only practical effect of adding the constant term is to slow the evaluation of the model. |
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