Abstract
The widespread demand of portable devices with imaging, multimedia, voice and data, has resulted in the requirement of efficiency power saving solutions to prolong battery life. The general converter modes are pulse width modulation (PWM) and pulse frequency modulation (PFM). But the efficiency of the PWM mode is low in light loading current and that of the PFM mode is low in heavy load. In order to maintain high efficiency, the dual-mode of PWM and PFM circuits have been presented. But these techniques usually didn’t find the best switching point. With the proposed buck converter, the technique to choose which mode can achieve high efficiency over wide loading range for improving the battery life. In order to increase the efficiency and decrease the area of the converter, dynamic partial shut down technique and combined PWM and PFM circuits are proposed. The converter is designed a 0.35um n-well CMOS process for a supply range of 2.7-5v which is compatible with state-of-the-art Li-ion batteries (2.7-5v).Simulation results show that the converter convert generates the output voltage of 2V while delivering up to 1000mA of load current with a maximum ripple of 8mV. An it’s maximum efficiency is 96.7%.