Abstract
With the exponentially increasing of portable battery-powered electronic equipments, such as mobile phones, digital cameras and so on, power management has becoming more and more critical and focus on reducing the power consumption. Low dropout (LDO) regulators is widely used in power management since it has a better load transient response, less output noise and few off-chip components compared to switch-mode regulators. However, there are some tradeoffs among stability, accuracy, transient response, regulation and off-chip components, etc.Two new architectures of LDO regulator are proposed in this thesis. First, the novel capacitor-free1 LDO regulator with voltage-controlled current source as a differentiator to increase the transient response is proposed. The conventional LDO regulator has to put the filtering capacitors at the output to ensure the stability and to reduce the voltage dip when load current changes. Therefore, the proposed LDO regulator is suitable for the System-on-Chip (SOC) applications and portable devices that need to reduce the volume and weight. Besides, the second proposed architecture of LDO regulator is based on the Miller compensation with voltage follower. It has the feature of fast transient response and good at both of line regulation and load regulation.All the circuits are implemented in TSMC .35 CMOS process. The mathematical analysis of loop-gain of frequency response, design issues and circuit implements are addressed in detail.