Biography
Enrollment Date: 2008
Graduation Date：2011
Degree：M.S.
Defense Date：2011.05.24
Advisors：Hanjun Jiang
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Low Dropout Linear Regulator Design and Design Automation
Abstract:
With the fast development of integrated circuit as well as the popularization of consumer electronic products, power management chips have obtained a prosperous market. Power management with high efficiency positively influences the entire system's performance. Low dropout linear regulator (LDO) as a kind of the power sources, serves as one of the best choices for engineers due to its character of low noise, high power supply rejection ratio, and simple peripheral circuit requirement. LDO with large load current driving ability is becoming the key point, but how to guarantee the stability during the entire load current remains to be the most challenging issue. Under this background, the paper proposed a low dropout linear regulator which is able to drive the load current as high as 300mA. The LDO is capable to provide a fixed voltage output of 3.3V when supply voltage varies from 3.5V to 5.5V. The dropout voltage is only 200mV when driving a load current of 300mA. Ahuja compensation method is used to guarantee the stability. A novel dynamic buffer is used to guarantee the circuit's stability as well as to improve the system's transient response. In addition, techniques such as over temperature protection, over current protection and reverse current protection are used to protect the chip from damage in abnormal states. The proposed structure is realized successfully with the CSMC 0.5um process. The architecture and the principle of the circuit are analyzed theoretically and we obtained the simulation results from Cadence. And finally the test result of the chip is given, which is in good agreement with the simulation results. With the experience of designing the LDO, a new automation tool is developed with Visual Basic 6.0. On this platform, an LDO can be synthesized automatically by two simple steps, of which the first step is choosing the process, and the second step is to configure the parameter of the LDO.