【作者】 杨超；

【导师】 陈浩；

【作者基本信息】 哈尔滨工业大学 ， 电子与通信工程（专业学位）， 2019， 硕士

【摘要】 随着电子产品的日趋发展,电子产品的种类以及电子产品的运行速度也是越来越快,电源管理IC作为每个设备的必备部分,它的稳定性以及纹波输出也变的越发的重要,低压差线性稳压器(Low Dropout Regulator,LDO),由于其较高的负载调整率、较高的线性调整率、较小的纹波电压输出、较好的输出噪声等特点得到了广泛的应用。然而在实际的产品项目应用中,会发现部分LDO会出现自激的现象,这主要是由于LDO作为一个闭环的系统,它的环路波特图影响它的环路稳定性,不同的负载下环路的波特图是变化的,所以在特定的负载下,就会出现LDO闭环环路系统不稳定的现象,同时如果LDO闭环环路特性不好,也直接影响着输出纹波的大小,经确认相关LDO的规格资料以及实际测试部分较好参数的LDO,发现目前市面上几乎所有品牌的LDO都无法满足在宽负载范围内有较好的环路稳定性以及低纹波输出,进而无法满足电子产品负载变化较大的需求,稳定性以及输出纹波无法得到最大限度的保障。因此,本文专门针对这一问题,对LDO进行深入的研究,研究和设计一种在2A负载范围内有较好的环路稳定性以及较低输出纹波的LDO。本文首先研究了LDO的分类、基本框架组成以及基本原理,对LDO的现状以及相关的技术进行了一定的概括、总结和分析,并依据信号与系统中关于闭环系统的稳定性判据以及SOC和其他消费类用电模块对于电源的纹波以及P SRR要求,提出了本论文设计所要达到的各项技术参数指标标准。接着为实现这一系列的技术指标,研究了LDO分支下的一种特有LDO,同时也是未来主流的低压差线性电源,CMOS LDO,由于目前传统的CMOS LDO原理框架结构中调整管结电容,负载电容以及误差放大器频率响应等都会随着负载的变化而出现变化,进而影响LDO闭环反馈系统的稳定性以及输出纹波,因此本文提出能够实现本论文设计要求的一种新的CMOS LDO原理框架结构,并对这种新的原理框架结构图内部各个部分做了详细的说明分析,明确该原理框架结构的技术实现方案,确保该技术为本论文后续技术研究有相应的支撑作用。其次,对于本文提出的CMOS LDO新原理框架结构实现技术方案中的主要部件:电流检测,做了详细的研究、分析以及电路仿真。由于LDO在宽负载范围内很难实现宽负载范围内的高稳定性以及低纹波输出,因此该部分电流检测电路的好坏,直接决定着LDO在不同的负载下采用什么样的误差放大器,进而决定整个LDO的稳定性以及输出纹波的大小。再次,新原理框架结构实现技术方案中的主要部件:误差放大器,做了详细的研究、分析以及电路仿真。误差放大器由于在宽负载范围内都有较好特性的设计难度很大同时成本也相当的高,所以本论文提出双误差放大器的电路结构,在不同的负载下切换不同的误差放大器,进而避免不同误差放大器在不同的负载条件下的缺点,突出各自的优点。然后,对于新的CMOS LDO原理框架结构中另外几个重要模块:调整管、轻载重载误差放大器切换开关以及单端信号转差分信号电路,进行了相关的研究、分析以及相应的电路仿真测试,确保了后续整个技术方案的可行性以及后续的系统联调测试仿真模型的顺利搭建。最后,本文将各部分搭建组合在一起,利用PSPICE仿真软件,结合所有模块的仿真参数条件,测试整个系统的环路曲线、负载跳变纹波以及PSRR,并通过不断的调试、测试以及仿真,达到论文设计之初的各项技术参数指标,满足2A负载范围内有好的环路特性以及低的输出纹波,进而完成本论文研究和设计一种在2A负载范围内稳定性以输出纹波较好的LDO的目的。更多还原

【Abstract】 With the development of electronic products,the types of electronic products and the running speed of electronic products are also faster and faster.As an essential part of every equipment,power management IC is becoming more and more important for its stability and ripple output.Low Dropout Regulator(LDO)has higher load adjustment rate,higher linear adjustment rate and better performance.The characteristics of small ripple voltage output and better output noise have been widely used.However,in the actual application of product projects,some LDOs will appear self-excitation phenomenon,which is mainly due to LDO as a closed-loop system,its loop baud diagram affects its loop stability.Loop baud diagram changes under different loads,so under specific loads,there will be LDO closed-loop system instability.At the same time,if LDO closed-loop system is unstable.The bad road characteristics also directly affect the output ripple size.After confirming the relevant LDO specifications and the LDO with better parameters in the actual test part,it is found that almost all brands of LDO on the market can not meet the requirements of better loop stability and low ripple output in the wide load range,and thus can not meet the larger load variation of electronic products,stability and transmission.The ripple can not be guaranteed to the maximum extent.Therefore,this paper is dedicated to this problem,in-depth study of LDO,research and design a LDO with better loop stability and lower output ripple in the 2A load range.Firstly,this paper studies the classification,basic framework and basic principle of LDO,summarizes and analyses the current situation of LDO and related technologies,and puts forward the technologies to be achieved in this paper according to the stability criterion of closed-loop system in signal and system,the ripple of power supply and PSRR requirements of SOC and other consumer power modules.Parameter index standard.Secondly,in order to achieve this series of technical indicators,a special LDO under the branch of LDO is studied.CMOS LDO,which is also the mainstream low-voltage-difference linear power supply in the future,will change with the change of load due to the adjustment of junction capacitance,load capacitance and frequency response of error amplifier in the framework of traditional CMOS LDO principle,and then affect the closed-loop feedback system of LDO.Stability and output ripple,so this paper proposes a new CMOS LDO principle framework which can meet the design requirements of this paper,and makes a detailed description and analysis of the internal parts of this new principle framework structure diagram,clarifies the technical implementation scheme of the principle framework structure,and ensures that the technology has a corresponding supporting role for the follow-up technical research of this paper.Secondly,the main components of the new CMOS LDO principle framework,current detection,are studied,analyzed and simulated in detail.Because it is difficult for LDO to achieve high stability and low ripple output in wide load range,the quality of current detection circuit directly determines what error amplifier LDO uses under different loads,and then determines the stability of the whole LDO and the size of output ripple.Thirdly,the main component of the new principle framework,error amplifier,is studied,analyzed and simulated in detail.Because the design of error amplifier has better characteristics in wide load range is very difficult and the cost is quite high,so this paper proposes the circuit structure of double error amplifier,which can switch different error amplifiers under different loads,so as to avoid the shortcomings of different error amplifiers under different load conditions and highlight their respective advantages.Then,for several other important modules in the new CMOS LDO principle framework: the regulator,the switch of the light-load and heavy-load error amplifier and the single-ended signal to differential signal circuit,relevant research,analysis and corresponding circuit simulation tests are carried out to ensure the feasibility of the whole technical scheme and the smooth construction of the subsequent system debugging test simulation model.Finally,this paper builds and combines all parts together,uses PSPICE simulation software,combines the simulation parameter conditions of all modules,tests the loop curve,load jump ripple and PSRR of the whole system,and through continuous debugging,testing and simulation,achieves the technical parameters at the beginning of the paper design,and meets the requirements of good loop characteristics and low transmission in 2A load range.The purpose of this paper is to study and design a LDO with good ripple stability in the 2A load range.更多还原