A monolithic peak current-mode buck converter with fast response for high speed DVS application

A monolithic peak current-mode step-down DC-DC converter with fast response for DVS application is presented in this paper. A novel fast on-chip soft-start circuit is used to reduce the overshoot voltage and inrush current. The loop without large capacitor compensation is adopted to increase the slew rate of the error amplifier, which can dramatically decrease the transient response time of the system. Meanwhile, automatic pulse width modulation (PWM) and pulse skip modulation (PSM) switching are used to improve conversion efficiency during the wide load range. The DC-DC converter has been fabricated with a standard 0.13 μm CMOS process. Experimental results show that the start-up time is less than 50 μs without the inrush current and overshoot voltage. The recovery time is less than 8 μs while the load current suddenly changes 300 mA. This converter can operate at 1.5 MHz with output voltage from 0.725 V to 1.5 V for DVS application. The up-tracking speed is about 31.25 μs/V and down-tracking speed is about 21.75 μs/V. Measured power efficiency is 84.2-93.8% for 1-400 mA load current.