Reseach And Design Of Fast Response Hybrid Buck Converter

Nowadays, the aggressive transistor scaling of semiconductor technologies has pushed the core operation frequency of SoC up to GHz range. Switching actions of millions of on-chip transistors cause extremely frequent and dynamic load fluctuations, making the design of on-chip power supplies very challenging. Switching converters are indispensable components in power management unit(PMU) for their high efficiency. Fast transient responses are crucial for switching converters to fit the demands of SoC. Pulse Width-Modulation(PWM) is the most popular control mode. However, the loop bandwidth is much lower than switching frequency and the slew-rate of inductor current is finite. Consequently, the transient response is severely deteriorated. In construct, LDO provides high bandwidth and fast transient response.Recently, the hybrid power converter, which consists of a parallel operation of switching converter and linear regulator, proves to be a successful combination of high loop bandwidth and good power efficiency. The schemes in developed for power amplifiers require the switching and linear regulation loops to work all the time, which complicates the compensation network design and degrades the power efficiency. When the system is operating in the steady state, the load current is supplied by the DC-DC converter, when the step load occurs, the transient current provided by the fast response LDO, while DC-DC regulator adjust the output current by the feedback loop, gradually increase or decrease its output current until the output voltage stability, and this time the LDO no longer provides current to the load, the load current is completely provided by the DC-DC converter.In this thesis, a fast transient response hybrid buck converter(HBC) with techniques to achieve automatic and seamless loop transition is proposed. The PWM control mode Buck converter combined with a push-pull LDO. Firstly this thesis analyzes the HBC main technical principles and theoretical basis, focuses on a digital auxiliary way to control push-pull configuration quiescent current, and pseudo-III compensation strategy for Buck converter and complete power stage design and every loop design according to the requirements of the relevant indicators. Then this thesis describes the design and simulations of the sub-modules contributing to the entire system feedback loop. Finally, the whole system described in this thesis is simulated to verification the transient response enhanced.