An Integrated Sliding-Mode Buck Converter With Switching Frequency Control for Battery-Powered Applications

Mobile applications necessitate nowadays huge digital resources. Power management of a digital systems-on-chip is based on dynamic voltage scaling. DC/DC converters used to supply the digital system-on-a-chips are facing stringent constraints with respect to load transients, line transients, and reference tracking. Hysteretic control is known as the most convenient control scheme with a fair tradeoff between transient performances, analog implementation and power consumption. Fixed-switching frequency hysteretic control has been experimented as well as full sliding-mode control. Transient performances are reduced due to latencies introduced in the switching frequency control. A new analog implementation of the sliding-mode control is presented here with switching frequency control using a particular analog phase-locked loop but preserve transient performances. The dc/dc converter is implemented in CMOS 130 nm. The switching frequency range has been voluntarily limited and excludes the possible integration of passive components. A hybrid demonstrator is presented with peak efficiency of 89% at 2-W output power.