Research And Design Of Segment Driving Technology Based On Buck DC-DC Converter In PWM Mode

Nowadays, smart phones, tablet computers and other portable electronic equipmenthave been widespread. As their size becomes smaller and smaller with more function,they have become multimedia equipment integrated communication and entertainmentfunction. Since battery technology is difficult to get breakthrough in a short time, howto reduce the power consumption of these systems from the perspective of powermanagement, extend the life time of portable devices becomes increasingly urgent.Compared with the linear voltage converter, DC-DC converter has been taken extensiveattention and application for its large current characteristics and excellent conversionefficiency. While, DC-DC power MOSFETs driving technology is a new way toimprove the efficiency of the system further.In this paper, the synchronous rectifier power MOSFETs driving technology inPWM mode BUCK circuit has been studied. And a real chip was manufactured to verifythis technology. By analyzing power loss on power MOSFETs, a new way to increaseefficiency was found and a novel driving technology, segment driving technology, wasproposed. The principle is that the power MOSFETs are divided into several parts andthe available conducting MOSFETs changes according to load current. In this way, theconducting loss and driving loss of the power MOSFETs achieve the best compromise,to improve the efficiency of the system.This thesis firstly introduced the background of the research and relatedfundamental theory of switch power supply. Secondly, emphatically analyzed the loss ofthe consumption on power MOSFETs and introduced two efficiency-improvetechnologies in light load condition. Then a BUCK DC-DC based on segment drivingtechnology was designed. The key modules such as the power MOSFETs, currentsampling circuit and time-to-digital converter and some important sub-blocks weredesigned. The conversion efficiency of the DC-DC converter is increased by thesub-circuit emulation, and overall the whole circuit and system simulation, optimizationof circuit design parameters. Finally, the proposed DC-DC converter with segmentdriving technology was manufactured by0.13m CMOS process, this technology was verified by test.