A fully-integrated 130nm CMOS DC-DC step-down converter, regulated by a constant on/off-time control system

A fully-integrated DC-DC step-down converter in a 130 nm 1.2 V CMOS technology is realized, with an integrated metal-track inductor and integrated MOS and MIM capacitors. The converter is designed to generate an output voltage of 1.2 V out of a 2.6 V power supply. No external components are required. The maximum power conversion efficiency is 52%, for a voltage conversion ratio of 0.46. This is a 12% improvement compared to a linear regulator. Higher values are likely to be reached using a converter with external components, which is not the case here. Stacked transistors are used to cope with the high voltage. A novel control system based on a constant on/off-time keeps the output voltage constant at load conditions from 0 mW to 180 mW. The converter operates in discontinuous, asynchronous switching mode. The switching frequency ranges from 30 Hz to 300 MHz.