Medium Frequency Output Impedance Limits of Switched-Capacitor Circuits

As an intrinsic power loss of switched-capacitor circuits (SCCs), capacitor charge-sharing loss reduces the system efficiency. In this article, the approach based on q-u curves of capacitors is proposed to calculate capacitor charge-sharing loss precisely. By considering both capacitor charge-sharing loss and conduction loss, the output impedance of an SCC with a finite output capacitance can be modeled accurately in medium switching frequency. Compared with the previous modeling techniques, the proposed modeling method called RLSL not only counts the output capacitor effect but also applies to a wide range of well-posed switched capacitor circuits. Several high-order SCCs are taken as examples to validate the accuracy of RLSL via simulations and experiments and it could be corroborated that RLSL can predict the output impedance precisely with the change of switching frequency, output capacitor, and duty cycle in the mid-band.