A Dual-Frequency Single-Inductor Single-Output DC-DC Converter Topology with Spur-Free Switching for Security Applications

A spur-free dual-frequency single-inductor single-output (DF-SISO) buck converter is presented. Dual-frequency operation enables on-chip integration of the output capacitor, and spur-free control eliminates spurious noise inherent to the switching of the converter. As a result, the proposed topology is suitable for secured IoT devices as the output can’t be directly probed, and the spur-free operation prevents leakage of load information through emissions. The converter is designed in 0.18µm CMOS and uses a 10-µH off-chip inductor and a 20-nH on-chip output capacitor. It handles 2.7-5 V input voltage range, and produces a programmable output within 0.6-1.8 V.