Ayan Karmakar · Kamaljeet Singh Si-RF Technology Si-RF Technology Ayan Karmakar Kamaljeet Singh (cid:129) Si-RF Technology 123 Ayan Karmakar Kamaljeet Singh Department ofSpace, Government U.R. RaoSatellite Centre of India Bangalore, Karnataka, India Semi-Conductor Laboratory Chandigarh,India ISBN978-981-13-8050-1 ISBN978-981-13-8051-8 (eBook) https://doi.org/10.1007/978-981-13-8051-8 ©SpringerNatureSingaporePteLtd.2019 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. 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The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore Foreword There has been tremendous growth in the miniaturization of RF circuits and com- ponents in both VHF/UHF and microwave regions. Efforts are already on the way for extending the same technologies to millimeter waves. Terahertz (THz) tech- nology isalso knocking atthe doorwithtremendouspotential for miniaturization. FortheminiaturizationofRFcircuits,theuseofmicrostripwasthefirststepand then MMICs have played a major role. The present book talks about the use of silicon substrate for manufacturing RF circuits and devices where even MEMS switches,filters,anddelaylinescanbefabricated.Thepresenttechnologyisbeing pursued seriously by researchers and manufacturers. In India, besides a few IITs and NITs, organizations like ISRO, DRDO, and CSIR are also working in this direction, and Semi-Conductor Laboratory, Department of Space/ISRO, has been established to give an impetus to this technology. Thepresentbook“Si-RFTechnology”touchesmanyaspectsofthedesignofRF circuits and components on a silicon substrate. Both the authors, Ayan Karmakar and Kamaljeet Singh, are experienced in the field and do have theoretical knowl- edge and practical experience. They have put their efforts to bring out this book, “Si-RFTechnology”.Thoughthesubjectisrathercomplex,theauthorshavemade it simple to be used and understood by working professionals, students, and researchers.Thisbookwillintroducethesubjecttotheprofessionalsadequatelyand enable them to go further for detailed study, design, and research. This book provides reasonably adequate design tips, formulae, etc., for the design of MICs, etc., and introduces the readers about various fabrication tech- nologiesincludingbulkandsurfacemicromachiningfabricationofpassivecircuits, planar antennas, MEMS switches, attenuators, and phase shifters, and even pack- aging concepts. v vi Foreword Iwishtocongratulatetheauthorsfortheireffortsincompilingvarioustopicsin one book and hope the readers will be benefited with the materials included. Bangalore, India Dr. Surendra Pal Dist FIETE, FNAE, FNASc Distinguished Scientist Associate Director and Program Director, Satellite Navigation Program at ISRO Satellite Centre Pune, India Ex-Vice Chancellor, DIAT Preface Roundtheglobe,amoderntrendinRForwirelesscommunicationisgoingtoward siliconRF(Si-RF)technology.Fromthelastdecade,manyworksofliteraturewere publishedonthis.Thistechnologydemonstratedtheviabilityofthevariouscircuits inbothactiveandpassivedomains,andthesameisinitiatedinourcountryalsoto reap the full potential. Realizing the need of this technology encompassing the ground-based applications as well as air-borne system at a higher range of fre- quencies, these developments are initiated by the authors. This book is the com- pilation of the work carried out by the group of authors encompassing design, modeling, fabrication, and characterization of RF circuits at various frequency bandsofsilicon.Communicationcircuitdevelopmentsparalleltosensortechnology arethemainmottoofthisresearchwork.Inthisbook,wehaveoutlinedthedesign andfabricationprocessstepsandfinallythetestresultsofallthecircuitstowardthe silicon substrate implementation of RF circuits. The work is initiated with L-band followed by S-, C-, X-, K -, K-, and finally K -band. Multiband circuits are also u a been part of the research work. New CMOS-compatible materials like polyamide/glass arealsopartofthisresearch work.Moreover,themodelingofthe high-frequency circuit having different substrate parameters makes this book more attractive. Comparative analysis is also carried out with the existing microwave substrate to demonstrate the viability of Si-RF technology. It shows promising performanceandgreatfutureaheadforthistechnologyintheneweraofRF-CMOS onasinglechip.Additionally,packagingaspectshavealsobeentoucheduponhere. In total, six chapters have been written here which cover the silicon-based micro- wave integrated circuits. Chapter 1 discusses the role of substrate in RF/microwave domain with a quantitative approach. The silicon substrate and its usage for high-frequency cir- cuits are highlighted, and various mitigation techniques have been elaborated with experimental data to validate the same. Chapter 2 briefly touches upon various fabrication techniques to realize 3D MEMS-based structure. The merits and demerits of the individual process are summarized. vii viii Preface Chapter 3 explains the silicon substrate as a potential candidate for high-frequency circuit realization starting from L-, S-, C-, X-, K -, and K -band. u a Single- as well as multiband circuit implementation of HRSi for RF usage is demonstrated. Direct conversion receiver module prototype is also realized which validates the proof of concept. Chapter 4 details the development of various planar antennas using a silicon substrate. Ultra-wideband antenna with band-notched characteristics has been demonstrated on Si, for the first time as per the authors’ knowledge. Further, micromachining concept has been adopted to realize the antenna array structure targetingK -bandapplication.Frequencyagilityconceptisanaddedfeatureofthis u development.Mathematicalmodelingofthesaidstructuremakestheconceptmore comprehensive for the people working in this domain. Chapter 5 covers the development of MEMS-based RF switch and its potential application. Detailed analysis (structural, mechanical, and analytical) of the struc- ture along with practical results provides comprehensive data to the researchers in this field. Finally, Chap. 6 outlines the packaging aspect in MEMS device, detailing practical implementation methodology. Further, for future generation packaging requirement, through-silicon via (TSV) is also modeled and detailed. Thisbookisintendedfortheresearchersandengineersinthisfieldwhowantto pursue RF circuit implementation at high frequency. It covers design, modeling, process, fabrication, and characterization aspects with practical examples without going much deeper into the mathematical descriptions so as to replicate the same easily and effectively by the designers. As this area has the potential for further extensive research, more details can be found in the attached references. We express our sincere appreciation to the colleagues at SCL and the family memberswhosupportedourendeavor.Also,seniormanagementwasconfidenton us and motivated us in spite of initial hurdles resulting in the creation of in-house characterization facilities. We are thankful to all the sources with which we inter- actedandsincerelyapologizeforomittingvariousworksofliteraturewhicharenot mentioned due to space constraint. Finally, for the time that has been stolen from ourfamily,weacknowledgethesupportofallfamilymembersandwillcontinueto seek forgiveness from them. Lastbutnotleast,wethanktheAlmightywithoutwhoseblessingsnojobcanbe successful. Chandigarh, India Ayan Karmakar Bangalore, Karnataka, India Kamaljeet Singh Acknowledgements It is our privilege and pleasure to express our profound senses of deep respect, sincere gratitude, and indebtedness to Sh. Surinder Singh, Director, SCL, for his constant support and encouragement. We are thankful to all the well-wishers for compelling us to think positively and overcoming various challenges encountered during this work. The comments and suggestions during various stages of this manuscriptimprovedthequality,andwewishtoacknowledgeallthereviewersfor their effort. WeareindebtedtoandsincerelythankSh.K.Nagachenchaiah,formerDirector, SCL, whose constant motivation, guidance, and suggestions not only made this workinterestingbutalsoforcedustobringoutthebest.Heiscreditedforcreating the infrastructure and providing unstinted support to enable us to complete the work. Wetake thisopportunitytothankallthecolleaguesinISRO,whosupportedus in this work. OurgratefulthanksareduetoMs.SwatiMaherishiandherteaminSpringerfor their unstinted support and cooperation in bringing out this edition which will be beneficial for students and academia. We express our gratitude to our family for their exemplary patience, under- standing, and cooperation during the preparation of this book. Lastbutthemost,wethanktheAlmightyforgivingusthepatienceandattitude in spite of various challenges encountered during this period. We will appreciate and gratefully acknowledge any constructive comments, suggestions, and criticisms from students and professionals. Ayan Karmakar Kamaljeet Singh ix Contents 1 Silicon Implementation of Planar Topologies . . . . . . . . . . . . . . . . . . 1 1.1 Microstrip and CPW Topologies . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Losses in Planar Topologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3 Substrate Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.4 Silicon Substrate and Associated Challenges . . . . . . . . . . . . . . . . 3 1.5 Modeling Aspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.6 Loss Compensation Techniques. . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.7 Summarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2 Fabrication Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.1 Bulk and Surface Micromachining. . . . . . . . . . . . . . . . . . . . . . . . 11 2.2 Wafer Bonding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2.1 Anodic Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.2.2 Eutectic Bonding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.3 Summarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3 Passive Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 3.1 Planar Balun (Single-Band Topology) . . . . . . . . . . . . . . . . . . . . . 21 3.1.1 Design Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3.1.2 Electromagnetic Analysis and Layout . . . . . . . . . . . . . . . . 23 3.1.3 Effect of Substrate Resistivity. . . . . . . . . . . . . . . . . . . . . . 25 3.1.4 Fabrication and Measured Results. . . . . . . . . . . . . . . . . . . 25 3.2 Power Divider (Multiband Topologies) . . . . . . . . . . . . . . . . . . . . 27 3.2.1 Dual-Band Power Divider . . . . . . . . . . . . . . . . . . . . . . . . 27 3.2.2 Receiver Concept (Multiband Topology). . . . . . . . . . . . . . 32 3.3 CPW-Microstrip Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.4 Summarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 xi