Current-slope-controlled adaptive-on-time DC-DC converter with fixed frequency and fast transient response

Abstract

An integrated fixed frequency adaptive-on-time DC-DC converter with fast transient response is presented. To achieve fixed frequency, the slope information of the inductor current is employed to adjust the on-time and keep the switching frequency constant at 1MHz to within 10% variation across the whole input/output and loading ranges. An integrated boost converter with an input voltage of 1.8V to 2.4V and a regulated output voltage between 3.0V and 3.6V was implemented with a 0.35µm CMOS process. Simulation results show that the switching frequency variation has ~40% and ~30% improvement over the traditional input/output voltage controlled adaptive-ontime technique when the load current changes from 0.1A to 0.8A and the inductor ESR changes from 0Ω to 0.2Ω, respectively. The load transient response time is about 20µs when the load current changes from 200mA to 800mA.