EE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 1EE C245 – ME C218Introduction to MEMS DesignFall 2009Prof. Clark T.-C. NguyenDept. of Electrical Engineering & Computer SciencesUniversity of California at BerkeleyBerkeley, CA 94720Lecture Module 2: Benefits of ScalingEE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 2Lecture Outline• Reading: Senturia, Chapter 1• Lecture Topics:ª Benefits of Miniaturizationª Examples( GHz micromechanical resonators( Chip-scale atomic clock( Micro gas chromatographEE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 3Benefits of Size Reduction: MEMSMEMS extends the benefits of size reductionbeyondthe electrical domain Performance enhancements for applicationdomains beyond those satisfied by electronicsin the same general categories SpeedPower ConsumptionComplexityEconomyFrequency Ç , Thermal Time Const. ÈActuation Energy È , Heating Power ÈIntegration Density Ç , Functionality ÇBatch Fab. Pot. Ç (esp. for packaging)Robustness g-Force Resilience Ç• Benefits of size reduction clear for IC’s in elect. domainª size reduction Ö speed, low power, complexity, economy• MEMS: enables a similar concept, but …EE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 4Vibrating RF MEMSEE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 5Basic Concept: Scaling Guitar StringsGuitar StringGuitarVibrating “A”String (110 Hz)Vibrating “A”String (110 Hz)High Q110 HzFreq.Vib. AmplitudeLow Qrromkfπ21=Freq. Equation:Freq.StiffnessMassfo=8.5MHzQvac=8,000Qair~50μMechanical ResonatorPerformance:Lr=40.8μmmr~ 10-13kgWr=8μm, hr=2μmd=1000Å, VP=5VPress.=70mTorr[Bannon 1996]EE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 6-60-50-40-30-20-1008.7 8.9 9.1 9.3Frequency [MHz]Transmission [dB]Pin=-20dBmInOutVPSharper roll-offSharper roll-offLoss PoleLoss PolePerformance:fo=9MHz, BW=20kHz, PBW=0.2%I.L.=2.79dB, Stop. Rej.=51dB20dB S.F.=1.95, 40dB S.F.=6.45Performance:fo=9MHz, BW=20kHz, PBW=0.2%I.L.=2.79dB, Stop. Rej.=51dB20dB S.F.=1.95, 40dB S.F.=6.45Design:Lr=40μm Wr=6.5μm hr=2μmLc=3.5μmLb=1.6μm VP=10.47VP=-5dBmRQi=RQo=12kΩ[S.-S. Li, Nguyen, FCS’05]3CC 3λ/4 Bridged μMechanical Filter[Li, et al., UFFCS’04]EE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 7-100-98-96-94-92-90-88-86-841507.4 1507.6 1507.8 1508 1508.21.51-GHz, Q=11,555 Nanocrystalline Diamond Disk μMechanical Resonator• Impedance-mismatched stem for reduced anchor dissipation• Operated in the 2ndradial-contour mode•Q~11,555 (vacuum); Q~10,100 (air)•Below: 20 μm diameter diskPolysiliconElectrodeRPolysilicon Stem(Impedance Mismatchedto Diamond Disk)GroundPlaneCVD DiamondμMechanical DiskResonatorFrequency [MHz]Mixed Amplitude [dB]Design/Performance:R=10μm, t=2.2μm, d=800Å, VP=7Vfo=1.51 GHz (2ndmode), Q=11,555fo= 1.51 GHzQ = 11,555 (vac)Q = 10,100 (air)[Wang, Butler, Nguyen MEMS’04]Q = 10,100 (air)§EE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 8vi+vi-vo+vo-VPVPλλ/2λ/4λ/2λ/4Port1Port1Port2Port2Port3Port3Port4Port4λλ/2λ/2Filter CouplerCom. Array CouplersDiff. Array Couplers[Li, Nguyen Trans’07]163-MHz Differential Disk-Array FilterEE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 9Wireless Phone90o0oA/DA/DRF PLLDiplexerFrom TXRF BPFMixer IMixer QLPFLPFRXRF LOXstal OscIQAGCAGCLNAAntennaFrequency [MHz]Transmission [dB]Micromechanical Bandpass FilterMicromechanical Bandpass FilterHigh Q and good linearity of micromechanical resonatorsHigh Q and good linearity of micromechanical resonatorsFilters for front-end frequency selectionFilters for front-end frequency selectionLinear MEMS in Wireless CommsEE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 10Wireless PhoneMiniaturization of RF Front Ends26-MHz Xstal Oscillator26-MHz Xstal OscillatorDiplexerDiplexer925-960MHz RF SAW Filter925-960MHz RF SAW Filter1805-1880MHz RF SAW Filter1805-1880MHz RF SAW Filter897.5±17.5MHz RF SAW Filter897.5±17.5MHz RF SAW FilterRF Power AmplifierRF Power AmplifierDual-Band Zero-IF Transistor ChipDual-Band Zero-IF Transistor Chip3420-3840MHz VCO3420-3840MHz VCO90o0oA/DA/DRF PLLDiplexerFrom TXRF BPFMixer IMixer QLPFLPFRXRF LOXstal OscIQAGCAGCLNAAntennaProblem: high-Q passives pose a bottleneck against miniaturizationProblem: high-Q passives pose a bottleneck against miniaturizationEE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 11Duplexer90o0oA/DA/DRXRF ChannelSelect PLLIQLPFLPFRXRF LOIQAGCAGCLNADuplexerRF BPFLNAFrom TXLNALNARF BPFRF BPFRF BPFWCDMAWCDMACDMACDMA--20002000DCS 1800DCS 1800PCS 1900PCS 1900LNARF BPFDuplexerLNARF BPFGSM 900GSM 900CDMACDMAFrom TXFrom TX90o0oIQTank÷(N+1)/NXstal OscAntenna• The number of off-chip high-Qpassives increases dramatically•Need: on-chip high-QpassivesMulti-Band Wireless HandsetsEE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 12All High-QPassives on a Single ChipWCDMARF Filters(2110-2170 MHz)CDMA-2000RF Filters(1850-1990 MHz)DCS 1800 RF Filter(1805-1880 MHz)PCS 1900 RF Filter(1930-1990 MHz)GSM 900 RF Filter(935-960 MHz)CDMA RF Filters(869-894 MHz)0.25 mm0.5 mmLow Freq. Reference Oscillator Ultra-High Q TankOptional RF Oscillator Ultra-High QTanksVibrating Resonator62-MHz, Q~161,000Vibrating Resonator62-MHz, Q~161,000Vibrating Resonator1.5-GHz, Q~12,000Vibrating Resonator1.5-GHz, Q~12,000EE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 13Chip-Scale Atomic Clocks (CSAC)EE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 14NIST F1 Fountain Atomic ClockVol: ~3.7 mVol: ~3.7 m33Power: ~500 WPower: ~500 WAcc: Acc: 11××1010––1515Stab: 3.3x10Stab: 3.3x10--1515/hr/hrPhysics PackagePhysics PackageAfter 1 sec ÖError: 10-15secAfter 1 sec ÖError: 10-15secLoses 1 sec every 30 million years!Loses 1 sec every 30 million years!EE C245: Introduction to MEMS Design LecM 2 C. Nguyen 8/20/09 15Benefits of Accurate Portable TimingSecure CommunicationsNetworked SensorsFaster frequency hop ratesFaster frequency hop ratesFaster acquire of pseudorandom signalsFaster acquire of pseudorandom signalsSuperior resilience against jamming or interceptionSuperior resilience against jamming or interceptionMore efficient spectrum utilizationMore efficient spectrum utilizationLonger autonomy periodsLonger autonomy periodsGPSFaster GPS acquireFaster GPS acquireHigher jamming marginHigher jamming marginFewer satellites neededFewer
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