A Two-Stage 12–1-V Converter Featuring Regulated Resonant SC Regulators and Collaborative Control Scheme

In the field of power converters for data centers, the two-stage architecture has received widespread attentions due to its various advantages. Especially, the switched-capacitor voltage regulator (SCVR) becomes popular as the second-stage converter owing to its high efficiency and power density. However, the SCVR suffers from poor voltage regulation and limited load capacity. To address these limitations, this article presents a two-stage converter featuring a regulated resonant switched-capacitor (ReSC) second-stage design. Thanks to the resonant operation of the ReSC, the converter achieves the superior power density and load capacity using a compact sub-nano-henry trace inductor. In addition, the resonant operation paves way for the voltage regulation, which is further employed for enhancing transient performances. Finally, to overcome the inherent efficiency versus voltage regulation tradeoff for the ReSC, a collaborative control scheme is built between the first and second stages, which adaptively adjusts the intermediate bus voltage to maintain the ReSC always in the efficient non-regulation mode for the entire output voltage range, leading to a high efficiency for a wide voltage and current range. By employing discrete GaNFETs for the first stage and 65-nm CMOS technology for the ReSC and controller design, the proposed two-stage converter achieves a measured system peak efficiency of 89.3% for 12:1-V conversion. With a 4-A/20-ns load current step, the measured undershoot voltage is 26 mV.