Design Of Average Current Mode PWM Buck Switching Power Supplies

Integrated PWM switching power supplies have been widely used in communication systems, computers, etc. Motivated by portable applications that demand high performance, switching power supplies are developed mainly aiming to high efficiency, high precision and small size. With high precision, average current mode controlled PWM DC-DC converters need measures to guarantee stable operation, which means to trade off between stability and quick transition response, as other current controlled ones. This article researches on how to design a stable ACM PWM buck converter with quick transition response through analyzing main transfer functions of the system. Design procedure is as below: the first step is to derive main transfer functions of power stage; and then to set up a complete small-signal model in complex frequency domain; finally, to accomplish systematic design applying Simulink. Several main blocks in control circuits are implemented in csmch0.6um standard CMOS process. According to Hspice simulation result, the system operation stably, with other performance required.