Table Of ContentCMOS HighEfficiency On-chip PowerManagement
ANALOGCIRCUITSANDSIGNALPROCESSINGSERIES
ConsultingEditor:MohammedIsmail.OhioStateUniversity
Forfurthervolumes:
http://www.springer.com/series/7381
John Hu • Mohammed Ismail
CMOS High Efficiency
On-chip Power Management
123
JohnHu MohammedIsmail
AnalogVLSILab AnalogVLSILab
DepartmentofElectricalandComputer DepartmentofElectricalandComputer
Engineering Engineering
TheOhioStateUniversity TheOhioStateUniversity
Columbus,OH Columbus,OH
USA USA
[email protected] [email protected]
OnleaveasATICProfessor
ChairandCampusDirector
TheKhalifaUniversityof
Science,Technologyand
Research(KUSTAR),UAE
ISBN978-1-4419-9525-4 e-ISBN978-1-4419-9526-1
DOI10.1007/978-1-4419-9526-1
SpringerNewYorkDordrechtHeidelbergLondon
LibraryofCongressControlNumber:2011934483
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To myparents,HuHeping andXiaoLijun.
To thememoryof mylatefather,Ismail
A.Elnaggar.
Preface
The world we live in today faces two fundamentalchallenges: the need to search
for renewable energy sources as replacements for depleting fossil fuels, and the
urgentnecessitytoreducegreenhousegasemissionsthatarecurrentlythreatening
the sustainability of the common and only habitat of human beings – the earth –
throughglobalwarming.
Withwindandsolarenergyharvestingstillfacingmajorhurdlesinconsistency
and reliability, and the safety of nuclear energy production called into serious
questions after the tragic Fukushima Daiichi nuclear disaster, improving energy
efficienciesinallaspectsisidentifiedasprobablythemosteffectivewaytoalleviate
bothcrisesintheshortterm.
Parallel to the energy and environmental crises at the megawatt level, the
consumer electronics industry is experiencing a similar but miliwatt level energy
crisisofitsown.Consumersappreciatethemultimediaandconnectivityaportable
devicecanprovide,butcontinuetodemandmorefunctionality,versatility,andmost
importantlylongerbatteryruntimeinthesamecompactsize.
Although there has been great progress in developing low cost, high energy
density battery technologies, enhancing the energy efficiency of the electronic
circuitsand systemsthroughaggressiveand innovativepowermanagementis still
consideredasthemosteffectiveandextremelynecessarymethodfortheelectronics
vendorstomeetconsumers’needsforalongerbatterylifeanddevelopproductsthat
willbecompetitiveinthemarket.Betterefficiencieswillalsoreduceheat,whichcan
beveryundesirableforendusers.
It is because of these reasons that there is a renaissance of interest in power
electronicswithintheindustrialandresearchcommunities.Technologiesofpower
electronics date back to days when power grids were first laid and electric plants
werecreated.Itisonlyrecentlythattheyseebrandnewapplicationsinawiderfield
ofinterest:smartgrid,powermanagementforconsumerelectronics,andbiomedical
applications,justtonameafew.
This book deals with the subject matter of power management IC design, or
integratedpowerelectronics,asaresponsetothegrowingneedforenergy-efficient
vii
viii Preface
electronics.Itis an emergingfield that haslately growninto an area ofits own in
parallel with conventional analog, digital, RF, and mixed-signal IC designs. This
field is unique in that it requires considerable amount of understanding of power
convertersandprinciples.ItisalsoverychallengingasitleveragesVLSItechniques
forimplementation.
In particular, this is the first monograph that addresses power management IC
design with an emphasis on high efficiency and full on-chip integration. High
efficiency is essential to extend battery life and reduce heat. Maximum on-chip
integration with fewer external components is the growing trend, as the physical
size,bill-of-materials,andmanufacturingcostallpointtoasystem-on-chipsolution
inamainstreamCMOSprocess.
This bookis dividedinto two parts with four chapters.Part 1 (Chaps. 1 and2)
presents the system point of view on power management in a green electronic
system. Part 2 (Chaps. 3 and 4) goes through details of circuit level power
managementICdesign.
Chapter1introducestheconceptofgreenelectronicsinfaceofthepowercrisisin
portableconsumerelectronics.Itenvisionsthestructureandnecessarycomponents
of such a system and identifies power management blocks as the bottle neck for
overallefficiencyimprovement.Asanintroduction,italsodescribestheuniqueness
ofpowermanagementICdesignandtherationalebehindthestudythereof.
Chapter 2 discusses power management at the system level. A holistic ap-
proach that involves system level software, SoC architecture, and silicon IPs is
presented. Meanwhile, the importance of sleep mode operation for portable and
battery-poweredapplicationsisdiscussed.Theruntimeextensionusingsleep-mode
efficiencyIPsisquantized,andthecircuitleveldesignofthesesleep-modeefficient
IPsbecomesathemeforthesecondpartofthebook.
Chapter 3 starts dealing with power management IC design by analyzing
linear regulators, especially the low drop-out (LDO) topology. Key performance
parameters of LDOs are listed. Their design challenges are also explained, and
existingperformanceenhancementmethodsare reviewed.Inthequestforfullon-
chip integration, designs of external capacitor-free LDOs are presented. A novel
sleep-mode ready, area-efficient capacitor- free LDO is proposed with testing
methodsandmeasurementresultspresented.
Chapter4movesontohighlyefficientpowermanagementICdesign,represented
by switching converters. The light-load efficiency of these converters is found to
be insufficient, and the root cause for the efficiency roll-off is identified. Existing
light-loadefficiencyboostingtechniquesarethendiscussed,followedbyaproposal
of a long-sleep model (LSM). A design example of a light-load efficient DC–DC
buck converter using the LSM is presented. The characteristics, implementation,
implication,andnoveltyoftheLSMarestudiedthoroughly.
This book will serve as a reference for analog and power management IC
design engineers in industry, as well as graduate students conducting research in
high efficiency electronics, power management, and analog IC design in CMOS
technologies. It will also be useful for test engineers, project leaders, design
managers,andindividualsinmarketingandbusinessdevelopment.
Preface ix
Thisbookhasitsrootinthe Ph.D.dissertationofthefirstauthorattheAnalog
VLSI Laboratory at the Ohio State University. We would like to thank all those
whosupportedus,includingourcolleaguesintheAnalogVLSILaboratoryandthe
ElectroscienceLaboratoryattheOhioStateUniversity,atFirst-passTechnologies
in Dublin, Ohio, and from Battery Management Solutions and Low Power RF
divisions of Texas Instruments. Last but not least, we would like to thank our
familiesfortheircontinuedsupportandunderstanding.
Dallas,Texas JohnHu
Columbus,Ohio MohammedIsmail
