Design Of Fully Integrated High-Efficiency Buck Converter

With the growing demand of the consumer electronics market and the development of semiconductor technology,portable electronic devices have been increasingly miniaturized,and the trade-off relationship between the lifetime and the volume of electronic products has become increasingly prominent.Therefore,power management unit with high performance has been one of the important modules in electronic devices,especially high-efficiency and fully integrated switching converter,since it can avoid the use of bulky and expensive off-chip inductor,which increases power density and reduces cost,and high-efficiency can increase battery life of electronic equipment.However,with the high integration of inductor and capacitor components,the switching frequency of converter will reach tens or hundreds of megahertz.And the efficiency under light-load will be greatly reduced due to reverse current and switching loss,which will cause battery performance deterioration in electronic device.Therefore,in high-frequency fully integrated applications,it is particularly important to improve the efficiency of switching converters,especially the light-load efficiency.This thesis proposes a fully integrated high-efficiency Buck converter based on adaptive size adjustment technology.The usage of an additional control calibration loop ensures the Buck converter operates in discontinuous-conduction-mode(DCM)at light load,thereby eliminating the loss caused by the reverse current and improving the efficiency of the Buck converter.Furthermore,the light-load efficiency can be improved by adaptive size adjustment technology.This thesis proposes a novel adaptive size adjustment method based on voltage control.The load current is estimated by the output voltage of error amplifier,then the optimal size of power switch transistor is selected accordingly,the switching loss is reduced and the light-load efficiency is improved.Compared with traditional adaptive size adjustment technology based on current control,this method eliminated the power loss and circuit delay caused by current sensor,which is essential for the improving light-load efficiency at high frequencies.Based on SMIC 0.18?m CMOS process,this work is designed and simulated by Cadence Spectre software.The results show that at a switching frequency of 100 MHz,the Buck converter reaches a maximum efficiency of 89.7% when the load current is 260 m A,and when the load current is 20 m A,a efficiency of 83.2% is achieved.