A 3-Phase Resonant Switched Capacitor Converter Delivering 7.7 W at 85% Efficiency Using 1.1 nH PCB Trace Inductors

• Published in: IEEE journal of solid-state circuits Vol. 50; no. 12; pp. 2861 - 2869
• Main Authors: Schaef, Christopher, Stauth, Jason T.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Capacitance; Capacitors; DC-DC converter; Density measurement; Inductance; Inductors; integrated voltage regulator; Power system measurements; resonant switched capacitor; switched capacitor; Switches
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2015.2462351

In recent years, there has been a push towards high-density and monolithic DC-DC converters to support applications such as performance and mobile computing, consumer electronics, and renewable energy. Switched capacitor (SC) converters have started to gain traction for a number of these applications, but are still subject to fundamental limitations that drive them towards expensive process options and high switching frequencies. Variable regulation is challenging with the SC approach, and comes at the cost of lower power density and efficiency. This work presents a resonant switched capacitor (ReSC) topology that addresses some of these challenges by introducing a small amount of inductance in series with the flying capacitor, eliminating charge-sharing losses and thus allowing efficient operation in a low-cost process option. The three-phase interleaved topology can deliver up to 7.7 W at 85% efficiency (power density of 0.91 W/mm 2 or 6.4 kW/in 3 ) using a bootstrapped n-channel power train and single-digit nH inductors embedded in a flip-chip assembly. We also present the first implementation of efficient, fully-variable conversion ratios in a silicon ReSC integrated circuit without reconfiguration or gain-hopping .