  Miller formula modified to take into account voltage drop on serial resistor
of an avalanche photodiode is considered. It is proven by experimental data
that modified Miller formula can describe operation of both regular and
micropixel avalanche photodiodes with good enough precision. It is shown that
operation parameters of the devices can be determined using a linear
extrapolation of the voltage-current curve for both regular avalanche
photodiode and the one operating in Geiger mode.
