Ring type switched-capacitor power supplies can be changed their step-up or step-down voltage ratio by controlling the pattern of their clocks without changing the circuit configurations. Their characteristics using several charge-transfer capacitors are verified by experiments and theoretical analyses. In the case where the number of the charge-transfer capacitors is increased form several tens to a few hundred, the characteristics are verified with the view for IC implementation in this project. The limit of the characteristics are clarified when the number of the charge-transfer capacitors is increased, under the conditions that the area of each integrated circuit is the same, namely the total capacitance and the total on-resistance, which means the on-resistance if all the switches are connected in parallel, are the same.
In the case of a series-parallel type SC transformer, assuming that the values of all charge-transfer capacitors and on-resistances of all switches are the same, t
he voltage waveform across each charge-transfer capacitor is the same. Then, the element number of the state vector does not increase, even if the number of the charge-transfer capacitors n is increased, and it is easy to obtain the output resistance as a general case. On the other hand, in the case of a ring type SC transformer, the voltage waveform across each charge-transfer capacitor is not the same, even if the values of all charge-transfer capacitors and on-resistances of all switches are the same. Then it is difficult to derive the output resistance as a general case.
In this project, a new simple method for deriving the output resistance is presented and the characteristics of a ring type SC transformer are derived as a general case. As the result, although the ring type SC transformer has a flexible step-up or step-down ratio, its output resistance is increased by the second power of the step-up ratio. In the future, these theoretical results will be verified by the experiments. Less