Challenges for fully-integrated resonant switched capacitor converters in CMOS technologies

Abstract

The inherent losses in switched capacitor (SC) converters limit the possibility of having high efficiency at high power densities in an on-chip context. Hence, techniques are being investigated to enhance the deficient capacitance energy utilization. Resonant switched capacitor (ReSC) converters have been shown to be a promising candidate for efficient, dense, granular on-chip power supplies. In this paper, we discuss the design of an ReSC converter which uses integrated on-chip inductance in CMOS technology. We focus on a 2-phase 2:1 ReSC converter with single inductor. We discuss the practical constraints of using the on-chip air-core inductor and how it will affect the area of the converter. Using different inductor implementations, we compare the performance of the ReSC and SC converters of the same area. The results indicate the advantage of the ReSC converter over the SC one when an inductor with a relatively small area and negligible contact resistance is used that could be feasible in 3D technology.