An Adaptive Constant-on-Time-Controlled Hybrid Multilevel DC-DC Converter Operating From Li-Ion Battery Voltages With Low Spurious Output

This article describes a multilevel hybrid plug-and-play dc-dc converter capable of converting a Li-ion battery input voltage range of 2.7-4.5 V to a system-on-chip voltage range of 0.6-1.3 V with an output spur as low as -53.5 dBm, a switching frequency variation of 0.13%, and peak efficiency of 88.6% at a corresponding power density of 0.061 W/mm2. The converter, designed in 65-nm CMOS, uses a small 470-nH inductor and is stable with a multilayer ceramic output capacitor with only a 2-m Ω series resistance. A fully on-chip adaptive constant-on-time controller is employed, enabling a minimum efficiency of 70% for load currents as low as 30 mA with a response time of 3 μ s from a rapid 1-A load current step, without any need for external power supplies or control circuits.