The Correct Equation for the Current Through Voltage-Dependent Capacitors

Two different equations for the current through voltage-dependent capacitances are used in the literature. One equation is obtained from the time derivative of charge that is considered as capacitance–voltage product:
${\it dQ/dt=d[C(V)V]/dt=C(V)[dV/dt]+V[dC(V)/dt].}$
In the second equation, the term
${\it V[dC(V)/dt]}$
does not exist:
${\it dQ/dt=} {\it C(V)[dV/dt]}$
. This paper clears the ongoing confusion caused by the difference between these two equations. We use the voltage-dependent parasitic capacitance of a commercial Schottky diode in reverse bias mode to test experimentally both equations. The result is that it is incorrect to add the term
${\it V[dC(V)/dt]}$
in the first equation with the measured capacitance. We also perform a theoretical analysis, which shows that the differential capacitance,
${\it C(V)=dQ/dV}$
, in the correct current equation corresponds to the physical parameters of the diode capacitance.