BICMOS INVERTER

BICMOS TECHNOLOGYBy: RAHIL SHARMARoll no. : 340/101TALK FLOWWhat is VLSIWhat is BiCMOSFEATURESCHARACTERSTICS OF CMOS, BIPOLAR and BICMOS TECHNOLOGYBiCMOS fabrication processCMOS inverterBiCMOS inverterComparison between CMOS and BiCMOSPros and ConsApplicationsConclusion2What is VLSI ?VLSI stands for very large scale integration and is the process of creating integrating circuits by combining thousands of transistors into a single chip.Invention of VLSI is based on the achievements in the field of semiconductor technology.Transistors were invented at Bell labs in 1947.Jack kilby at texas instruments in 1958 was first to make a integrated circit ready.It elimnates the use of discrete components, wires and manual assembly of components. Eg. Microprocessor,controllers etc.33WHAT IS BiCMOSBipolar compatible CMOS(BiCMOS) technology:Introduced in early 1980sCombines Bipolar and CMOS logic

CMOS BIPOLARLow power dissipation High speed High packing density High output driveBiCMOS4

Features:The objective of the BiCMOS is to combine bipolar and CMOS so as to exploit the advantages of both the technlogies.Today BiCMOS has become one of the dominant technologies used for high speed, low power and highly functional VLSI circuits.The process step required for both CMOS and bipolar are almost similar The primary approach to realize high performance BiCMOS devices is the addition of bipolar process steps to a baseline CMOS process.The BiCMOS gates could be used as an effective way of speeding up the VLSI circuits.The applications of BiCMOS are vast.Advantages of bipolar and CMOS circuits can be retained in BiCMOS chips.BiCMOS technology enables high performance integrated circuits ICs but increases process complexity..5Characterstics of Bipolar TechnologyHigher switching speedHigher current drive per unit area, higher gainGenerally better noise performance and better high frequency characteristicsImproved I/O speed (particularly significant with the growing importance of package limitations in high speed systems). high power dissipationlower input impedance (high drive current)low packing densitylow delay sensitivity to loadIt is essentially unidirectional.

6Charactestics of CMOSLower static power dissipationHigher noise marginsHigher packing densityHigh yield with large integrated complex functionsHigh input impedance (low drive current)Scaleable threshold voltageHigh delay load sensitivityLow output drive current (issue when driving large capacitive loads)Bi-directional capability (drain & source are interchangeable)A near ideal switching deviceLow gain

7Characterstics of Bicmos TechnologyIt follows that BiCMOS technology goes some way towards combining the virtues of both CMOS and Bipolar technologiesImproved speed over purely-CMOS technologyLower power dissipation than purely-bipolar technology(Lower power consumption than bipolar)Flexible I/Os for high performance Improved current drive over CMOSImproved packing density over bipolarHigh input impedanceLow output impedanceHigh Gain and low noise

8Cmos fabrication9

BiCMOS FABRICATION PROCESSCMOS process BIPOLAR process1 . N well 1. n collector2. P base doping(extra step)3. PMOS source and drain 3. p+ base contact4. NMOS source and drain 4. n+ emitterAdapted from A.R.Alvarage et al.,An overview of BiCMOS Technology and Applications,IEEE International Symposium on Circuits and Systems,1-3 May,199010BiCMOS CROSS-SECTION

Adapted from J. M Rabaey, Digital Integrated Circuits: A Design Prespective, NewJersey: Prentice-Hall, Inc., 1996.

11BiCMOS process flow steps:

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18CMOS INVERTER IPVDDGNDOP Adapted from www2.eng.cam.ac.uk/~dmh/3b2/invert.htmCIRCUIT DIAGRAM 19BASIC BiCMOS INVERTER

Adapted from J. M Rabaey, Digital Integrated Circuits: A Design Prespective,New Jersey: Prentice-Hall, Inc., 1996.

20CONVENTIONAL BiCMOS INVERTER

Adapted from J. M Rabaey, Digital Integrated Circuits: A Design Prespective,New Jersey: Prentice-Hall, Inc., 1996.21PULL UP EVENT

C loadAdapted from Sung-Mo Kang,Yusuf Leblebici,CMOS Digital Integrated Circuits:Analysis and Design,Tata McGraw-Hill,Third edition,2003,p.547.22PULL DOWN EVENT

C loadAdapted from Sung-Mo Kang,Yusuf Leblebici,CMOS Digital Integrated Circuits:Analysis and Design,Tata McGraw-Hill,Third edition,2003,p.550.

23BiCMOS VS. CMOS

CMOSBiCMOSVTC comparison Adapted from www2.eng.cam.ac.uk/~dmh/3b2/invert.htm

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Nfbdf,fmnsdvnv,sndkmvnmdnvn,fnv24SPEED COMPARISON

Adapted from Larry Wissel and Elliot L. Gould,Optimal Usage of CMOS within a BiCMOS Technology,IEEE J. of solid-state circuits, Vol. 27, No. 3, March1992

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DELAY COMPARISONscaling of the technological parameters leads to the scaling of the device parameters

Adapted from Larry Wissel and Elliot L. Gould,Optimal Usage of CMOS within a BiCMOS Technology,IEEE J. of solid-state circuits, Vol. 27, No. 3, March 1992

26AREA COMPARISON

AAREAC COMPLEXITYAdapted from H.Klose et al.,Bicmos,a tehnology for High speed/High density ICs,IEEE international conference on Computer Design:VLSI in computers and proessors,2-4 Oct.,198927PROS OF BiCMOSImproved speed over CMOSImproved current drive over CMOS Improved packing density over bipolarLower power consumption than bipolarHigh input impedanceLatchup immunity2828CONS OF BiCMOSIncreased manufacturing process complexitySpeed degradation due to scalingThe efficiency of BiCMOS device increased by 2 and cost increased by 1.3 to 1.5 as compared to CMOS.

Adapted from Paul G. Y. Tsui et al.,Study of BiCMOS Logic Gate Configurations for Improved Low-Voltage Performance, IEEE J. of solid-state circuits, Vol. 28, No 3. March 1993.

29APPLICATIONSFull custom ICsSRAM,DRAMMicroproessor,controllerSemi custom ICsRegister,FlipflopStandard cellsAdders,mixers,ADC,DACGate arrays30BiCMOS PRODUCTS

W-CDMA DCR

SiGe BiCMOS GPS CIRCUITGSM 900 POWER AMPLIFIER

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CONCLUSION The extra process complexity requires chip manufacturers to command a premium for BiCMOS products. In the analog market the ability to integrate large mixed systems provides the compelling cost advantage of BiCMOS; this market is still emerging.BiCMOS is a complement to pure CMOS and Bipolar technologies in important system application areas. One of the main challenges facing BiCMOS design is to maintain its performance gain at lower voltage levels.32 REFERENCES[1]Kiat-Seng Yeo et al.,CMOS/BiCMOS ULSI:Low voltage,Low power,Pearson Education,Inc., First edition,2002.[2]Sung-Mo Kang,Yusuf Leblebici,CMOS Digital Integrated Circuits:Analysis and Design,Tata McGraw-Hill,Third edition,2003.[3]E.A.Gonzalez,BiCMOS processes,trends and applications,DLSU ECE,Technical report,Nov.29,2004.[4]A.R.Alvarez et al.,An overview of BiCMOS technology and applications,IEEE International Symposium on Circuits and Systems,1-3 May,1990.[5] T. Sakurai, A review on low-voltage BiCMOS circuits and a BiCMOS vs. CMOS speed comparison, Proceedings of the 35th Midwest Symposium on Circuits and Systems, vol. 1, Aug. 9-12 1992.[6] J. M Rabaey, Digital Integrated Circuits: A Design Prespective, NewJersey: Prentice-Hall, Inc., 1996.[7] J. P. Uremuya, Circuit Design for CMOS VLSI, Massachusetts: Kluwer Academic Publishers, 1992.[8] Adapted from H.Klose et al.,Bicmos,a tehnology for High speed/High density ICs,IEEE international conference on Computer Design:VLSI in computers and proessors,2-4 Oct.,1989[9] Larry Wissel and Elliot L. Gould,Optimal Usage of CMOS within a BiCMOS Technology,IEEE J. of solid-state circuits, Vol. 27, No. 3, March 1992[10] Paul G. Y. Tsui et al.,Study of BiCMOS Logic Gate Configurations for Improved Low-Voltage Performance, IEEE J. of solid-state circuits, Vol. 28, No 3. March 1993.[11] D.L.Harame,Current Status and Future Trends of SiGe BiCMOS Technology IEEE transactions on electron devices, vol. 48, no. 11, november 2001[12]Adapted from D.Harame et al.,The Emerging Role of SiGe BiCMOS Technology in Wired and Wireless Communications, Fourth IEEE International Caracas Conference on Devices, Circuits and Systems, Aruba, April 17-19, 2002.

33THANK YOUQ U E R I E S ?34