Boost The Power Management Circuit Design, The Internal Ldo

The power management solution involved in this thesis comes from a horizontal cooperation project with a company in Taiwan. In the circumstance of low dissipation, high efficiency and intelligence of power management products, an integration solution is introduced that low drop-out (LDO) linear voltage regulator supplies for the inner circuits of boost voltage converter. According to the design of LDO with buffer stage is designed in the thesis,which is achieved by 0.6μm 30V BCD technology. It can produce an invariable output voltage of 5V with the input voltage from 6V to 13V in the region of -25℃to 85℃. Its drop voltage is only 120mV under typical load current of 12.5mA.The principal of the project and specifications of LDO is firstly expatiated in this thesis and then the arcitectrue of the voltage regulator is introduced, which is composed of sub blocks such as error amplifiers, references and protection circuits. Furthermore, the author pays great attention on studying how to drive large capacitor, at the level of 100pF by amplifiers. Finally, the simulation results of the regulator are demonstrated.The core of the thesis is the analysis of the regulator's architecture and the design of the references.In the part of architecture design, LDO is constructed based on the study of three kinds of structure topology. A useful method on loop compesation is shown by modifying the feedback net. Based on Miller theorem and Root Locus theorem, Miller-Path-Compensation (MPC) amplifier is introduced to drive large capacitor, which helps decreasing the static current of buffer stage and controlling power transisitor better. MPC technique has also been used to design three-stage amplifers.The creative Current Reference controlled by Feedback (CRF) is a practical improvement on traditional bootstrap current reference. The resistant current path in the new reference shortens its response time. Using the same parameters and the same technology model, the response time of the new reference is only 1μs, but that of the typical one is 120μs. In the part of the voltage reference, a new reference with high order temperature compensation is realized on the base of band-gap voltage reference with linear temperature compensation. Correctional voltage steming from nonlinear current is introduced into reference by I-V method in order to correct the curve of reference's temperature characteristic. Finally, its temperature coefficient is only 3.53ppm/℃over the range of -40℃to 100℃.The simulation results of the system show the satisfaction to both function targets and characteristics. It is a worthwhile and valuable experience.