| A system with computer function has been integrated in units as small as cellphones nowadays. Recently, the requirements of the technologies change a lot. So the technology of the electronic products also develops rapidly. More and more products appear in the market, such as mobile power pack, wireless mouse, wireless watch and etc. As the main power management chips, power supply is widely used in the electronic products’ application fields, such as LDO linear regulator and boost DC-DC converter.This dissertation follows the development direction of the electronic theory and application. Key theories and design methods of circuits and structures are mainly researched in items of LDO and boost DC-DC converters. Relevant optimization design methods and the specific realization circuits are proposed. The main work and innovations of this dissertation are as follows.1. A high voltage LDO with dynamic compensation network is proposed and it is implemented in 0.6μm 40V BCD technology. The proposed LDO makes use of high voltage tolerance transistors to take most of the voltage in each path, thus satisfying the requirement of wide input range. Besides, the proposed dynamic compensation network can achieve a great stability performance for the LDO structure under different load current and input supply conditions. In addition, different output voltages are implemented in this work and the transient response in each situation is improved. The conventional miller compensation and dynamic compensation network are combined together in this technology, and the design of the compensation network in the high voltage loop stability is realized by adding resistors and capacitors of normal voltage tolerance. This compensation method is designed for wide range low dropout regulator, so it can be widely used in many different application conditions and the loop stability can be guaranteed as well.2. A high precision low power consumption LDO is presented. The low quiescent current LDO is realized with a combination structure of a bandgap and an error amplifier. The circuit is achieved with a combined structure which is able to obtain a low quiescent current, since the current for the specific bandgap reference can be omitted. The transient response enhancement circuit can activate an additional path to control the gate voltage of the pass transistors which assist in monitoring the variation at the output voltage during steady and transient state. According to restrictions of the process and the product requirements, this proposed LDO is implemented in 0.6μm 40V BCD technology. The LDO has a quiescent current of 2.8μA and is able to deliver a 50mA load current.3. A high efficiency and high performance boost DC-DC converter is proposed. The operation procedure is mainly analyzied and the linear model is calculated. Besides, three kinds of core technologies to improve the efficiency and performance of the circuitry are presented, such as high efficiency anti-ring technology, LDO-like soft-start technology and high efficiency mode switching technology. Firstly, an anti-ring block is introduced in the high efficiency anti-ring technology to blank the switching ringing phenomena generated from the coupling of the inductor and capacitors, thus saving extra ringing power consumption. Secondly, the analysis of the LDO-like soft-start technology begins from the pre-charge stage of the output voltage, and a pre-charge circuit similar to LDO sampling structure during soft-start procedure is presented. Finally, a three-mode switching method is proposed. The relationship between the operational process and the logic signals is analyzed in detail. The circuit is implemented in 0.35μm 5V BCD process, and the chip area is 2.24mm2.4. A synchronous boost DC-DC converter with constant current mode control is presented. The aim is to enlarge the application range, meeting the requirements in markets of mobile power pack. Historically, the boost DC-DC converters applied in a mobile power pack only have a constant voltage control mode loop to provide a fixed output voltage for discharging and usually use short circuit protection method to avoid chip damage when the output current exceeds the limitation value. A constant current control loop is introduced except for the constant voltage control loop in the proposed boost DC-DC converter. The double loop concept makes it possible to realize the synchronous charging in a mobile power pack. The constant current loop is achieved with a selection circuit of reference voltage, an additional operational trans-conductance amplifier and a feedforward compensation technology, thus guaranteeing a continuous charging current for loading which can strongly enhance the battery life. During the design of the double loop, core problems such as loop control, loop compensation and signal amplification are analyzed in detail, thus improving the performance of the whole working system. The circuit is implemented in 0.6μm 5V BCD process, and the chip area is only 2.484mm2. |
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