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1、LDO線性穩(wěn)壓器設(shè)計(jì)畢業(yè)論文摘要隨著電源管理IC技術(shù)的不斷發(fā)展,高性能低成本的電源管理芯片越來(lái)越受到用戶的青睞。LDO線性穩(wěn)壓器以其低噪聲、高電源抑制比、微功耗和簡(jiǎn)單的外圍電路結(jié)構(gòu)等優(yōu)點(diǎn)而被廣泛應(yīng)用于各種直流穩(wěn)壓電路中。為適應(yīng)電源市場(chǎng)發(fā)展的需要,結(jié)合LDO系統(tǒng)自身特點(diǎn),設(shè)計(jì)了一款低功耗、高穩(wěn)定性LDO線性穩(wěn)壓器。本文首先簡(jiǎn)要介紹了LDO線性穩(wěn)壓器的工作原理與基本性能指標(biāo)。其次,從瞬態(tài)、直流、交流三方面對(duì)系統(tǒng)結(jié)構(gòu)進(jìn)行深入研究,闡述LDO穩(wěn)壓器的設(shè)計(jì)要點(diǎn)與各種參數(shù)的折衷關(guān)系。隨后從低功耗設(shè)計(jì)的角度出發(fā),對(duì)各子模塊結(jié)構(gòu)進(jìn)行優(yōu)化,從而確立最終的系統(tǒng)架構(gòu)。通過(guò)建立LDO電路的交流小信號(hào)模型,計(jì)算得到
2、系統(tǒng)的環(huán)路增益并由此推出電路中零極點(diǎn)的分布位置從而獲得研究系統(tǒng)穩(wěn)定性問(wèn)題的途徑。針對(duì)文中采用的兩級(jí)級(jí)聯(lián)誤差放大器直接驅(qū)動(dòng)調(diào)整管柵極的拓?fù)浣Y(jié)構(gòu),引入嵌套式密勒補(bǔ)償和動(dòng)態(tài)零點(diǎn)補(bǔ)償兩種方法來(lái)保證系統(tǒng)的穩(wěn)定性要求。討論了嵌套式密勒補(bǔ)償中調(diào)零電阻可能存在的位置,確定最合適的補(bǔ)償結(jié)構(gòu)從而有效地消除了右半平面零點(diǎn)對(duì)系統(tǒng)穩(wěn)定性的影響。最后分析了各子模塊電路的結(jié)構(gòu)與工作原理,并給出了LDO系統(tǒng)模塊與整體仿真的結(jié)果與分析。電路設(shè)計(jì)采用了CSMC0.6umCMOS工藝模型,對(duì)LDO穩(wěn)壓器在不同的模型、輸入電壓、溫度組合下進(jìn)行前仿真驗(yàn)證。結(jié)果表明:電路不帶負(fù)載的靜態(tài)電流為1.79uA,系統(tǒng)帶寬幾乎不隨負(fù)載變化,在
3、輸出電流范圍內(nèi)能保證較好的穩(wěn)定性。關(guān)鍵詞:線性穩(wěn)壓器,低壓差,嵌套式密勒補(bǔ)償,動(dòng)態(tài)零點(diǎn)補(bǔ)償,低功耗12AbstractWithrapiddevelopmentofpowerICtechnology,highperformancelowcostpowermanagementchipsbecomemoreandmorepopular.LDOlinearregulatoriswidelyusedinvariouskindsofDCregulatingvoltagecircuits,forthebenefitsoflownoise,highpowersupplyrejectionratio(PSR
4、R),micropowerloss,andsimpleperipheralstructureetc.Inordertomeettheneedsofpowermarketdevelopment,combiningwithselffeaturesofLDOsystem,thisthesisproposesakindofLDOlinearregulatorwithlowpowerandexcellentstability.Firstly,thisthesisgivesabriefintroductiononworkingprinciplesandbasicindicatorsofLDOregul
5、ator.SystemstructurewillbedeeplydiscussedinTRAN,DC,ACthreeaspectsanddesigningkeypointsalongwithvariousparametertrade-offrelationshipswillbeexpoundedsubsequently.Then,optimumseverysub-moduleanddeterminesthefinalsystemarchitecturefromtheangleoflowpowerdesign.Inordertoobtainthepathtoresearchonstabili
6、tyofLDOsystem,calculatesloopgainanddeduceszero-poledistributionbysettingupACsmallsignalmodels.Nestedmillercompensation(NMC)andTracking-frequencycompensationwillbeintroducedtoensurethestabilityofLDOtopologicalstructurewhichadoptstwostagecascadeerroramplifierdrivingpasselementdirectly.Discussesproba
7、blesituationofnullingresistorinNMCcircuits,andeliminateseffectofright-half-planezeroeffectivelybyfixingabestcompensationstructure.Analyzesstructureandworkingprincipleofeverysub-moduleindetail,simulationresultsofw