Single-Inductor Multioutput-Level Buck Converter for Reducing Voltage-Transition Time and Energy Overheads in Low Power DVS-Enabled Systems

Abstract

Dynamic voltage scaling (DVS) is a useful technique to optimize performance and efficiency of CMOS digital processors using dc–dc converters that require to meet extremely fast slew rate demand. However, there exist conflicting design criteria in existing DVS power supply architectures. This paper proposes a single-inductor multioutput-level buck converter for low power DVS-enabled systems. Under the time optimal voltage transition recovery, the proposed architecture: first, achieves the performance much beyond system's physical limits compared to conventional synchronous and multiphase buck converter based architectures; and second, can overcome conflicting power circuit design criteria in existing architectures. Also, a high-resolution quantized voltage can be realized by using a voltage-dithering technique. An analytical framework is considered to formulate various processor and converter-induced energy overheads. A comparative study is shown to evaluate the usefulness of the proposed architecture over the existing approaches under frequent voltage transitions. A prototype single-inductor four-output-level buck converter is tested and the performance improvements are demonstrated using test results.