High Level Model And Circuit Design Of CMOS Buck Converter

Considering the application trend of power management, the position of linear converters is being replaced by switch power converters. Meanwhile, the integration is also a significant trend for power management chips like other semiconductor products. Anyway, LDO, linear converters and DC/DC, switch power converters, are still two most popular powe management products at present.This dissertation presents the basic configuration and theory of LDO, and introduces typical Buck DC/DC and Boost DC/DC circuits in detail. Pulse Width Modulation (PWM) and Pulse Frequency Modulation (PFM), which are two important modulations are discussed and compared with each other. In addition, this paper generally describes the basic Buck converter topology with synchronous rectification.For the DC/DC converter analysis and design, we can use mathematics modeling such as analytical method and state space method. This paper adopts state vector averaging and linearization method, based on Simulink, setting up a system model of current controlling PWM buck converter, to simplify the design process. Then, the inner circuits are verified with the model. Afterwards, the paper designs a Buck DC/DC converter with a P-MOSFET integrated inside. It realizes a high efficiency Buck converter, through controlling the duty ratio according to the load current to switch the modulation model between PWM and PFM. Furthermore, this paper also presents some critical sub-circuits of DC/DC converter.