Integrated Micromechanical Circuits for RF Front-Ends · C. T.-C. Nguyen, “Integrated...

C. T.-C. Nguyen, “Integrated Micromechanical Circuits for RF Front-Ends,” SSCS Dist. Lec.—Fort Collins., 11/30/07

Integrated Micromechanical Circuits for RF Front-Ends

Clark T.-C. Nguyen

Dept. of Electrical Engineering & Computer SciencesUniversity of California at Berkeley

Berkeley, California 94720E-mail: [email protected]

IEEE SSCS Dist. Lec.—Fort CollinsNov. 30, 2007


Outline

• Introduction: Miniaturization of Transceiversneed for high-Q

• Micromechanical Resonatorsclamped-clamped beamsmicromechanical disks

• Micromechanical Resonator Oscillators• Micromechanical Circuits

micromechanical filtersimpedance matchingMSI mechanical circuits

• Conclusions


Wireless Phone

Rec

eive

dPow

er

FrequencyωRF

DesiredSignal

Motivation: Miniaturization of RF Front Ends

90o0o

A/D

A/D

RF PLL

Diplexer

From TX

RF BPF

Mixer I

Mixer Q

LPF

LPF

RXRF LO

XstalOsc

I

Q

AGC

AGC

LNA

Antenna


Wireless Phone

Rec

eive

dPow

er

FrequencyωRF


90o0o

A/D

A/D

RF PLL

Diplexer

From TX

RF BPF

Mixer I

Mixer Q

LPF

LPF

RXRF LO

XstalOsc

I

Q

AGC

AGC

LNA

Antenna

Need high Q to minimize loss

lower noise figure


lower noise figureHighly selective

frequency filteringHighly selective

frequency filtering


Wireless Phone

FrequencyωRF


90o0o

A/D

A/D

RF PLL

Diplexer

From TX

RF BPF

Mixer I

Mixer Q

LPF

LPF

RXRF LO

XstalOsc

I

Q

AGC

AGC

LNA

Antenna


lower noise figure


lower noise figureHighly selective

frequency filteringHighly selective

frequency filtering

DesiredSignal


Wireless Phone

FrequencyωRF


90o0o

A/D

A/D

RF PLL

Diplexer

From TX

RF BPF

Mixer I

Mixer Q

LPF

LPF

RXRF LO

XstalOsc

I

Q

AGC

AGC

LNA

Antenna

DesiredSignal

Need high Qor low loss

components to do this

Need high Qor low loss

components to do this


Wireless Phone

So Many Passive Components!

26-MHz XstalOscillator


DiplexerDiplexer

925-960MHz RF SAW Filter925-960MHz

RF SAW Filter

1805-1880MHz RF SAW Filter


897.5±17.5MHz RF SAW Filter


RF Power Amplifier

RF Power Amplifier

Dual-Band Zero-IF Transistor Chip


3420-3840MHz VCO

3420-3840MHz VCO

90o0o

A/D

A/D

RF PLL

Diplexer

From TX

RF BPF

Mixer I

Mixer Q

LPF

LPF

RXRF LO

XstalOsc

I

Q

AGC

AGC

LNA

Antenna

Problem: high-Q passives pose a bottleneck against miniaturizationProblem: high-Q passives pose a bottleneck against miniaturization


Multi-Band Wireless Handsets

Duplexer

90o0o

A/D

A/D

RXRF ChannelSelect PLL

I

Q

LPF

LPF

RXRF LO

I

QAGC

AGC

LNA

Duplexer RF BPF

LNAFrom TX

LNA

LNA

RF BPF

RF BPF

RF BPF

WCDMAWCDMA

CDMACDMA--20002000

DCS 1800DCS 1800

PCS 1900PCS 1900

LNA

RF BPF

Duplexer

LNA RF BPF

GSM 900GSM 900

CDMACDMA

From TX

From TX90o

0o

I

Q

Tank

÷ (N+1)/N XstalOsc

Antenna

• The number of off-chip high-Qpassives increases dramatically

• Need: on-chip high-Q passives


Thin-Film Bulk Acoustic Resonator (FBAR)

• Piezoelectric membrane sandwiched by metal electrodesextensional mode vibration: 1.8 to 7 GHz, Q ~500-1,500dimensions on the order of 200μm for 1.6 GHzlink individual FBAR’s together in ladders to make filters

Agilent FBAR

• Limitations:Q ~ 500-1,500, TCf ~ 18-35 ppm/oCdifficult to achieve several different freqs. on a single-chip

h

freq ~ thicknessfreq ~ thickness


All High-Q Passives on a Single Chip

WCDMARF 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 mm

0.5 mm

Low Freq. Reference Oscillator Ultra-High

Q Tank

Optional RF Oscillator

Ultra-High QTanks

Vibrating Resonator62-MHz, Q~161,000

Vibrating Resonator62-MHz, Q~161,000

Vibrating Resonator1.5-GHz, Q~12,000

Vibrating Resonator1.5-GHz, Q~12,000


Vibrating RF MEMS Wish List

•• MicroMicro--scale waferscale wafer--level fabricationlevel fabricationwould like >1,000 parts per die to at least achieve large-scale integration (LSI) complexityneed wafer-level packaging

•• SingleSingle--chip integrated circuit or chip integrated circuit or system capabilitysystem capability

discrete parts not interestingmust allow many different frequencies on a single-chipneed on-chip connectivityintegration w/ transistors desiredneed real time reconfigurability

•• QQ’’s >10,000 at RF might have a s >10,000 at RF might have a revolutionary impactrevolutionary impact

Frequencies should be determined by lateral

dimensions (e.g., by layout)

Frequencies should be determined by lateral

dimensions (e.g., by layout)

Best if systems can be reconfigured w/o the need

for RF MEMS switches

Best if systems can be reconfigured w/o the need

for RF MEMS switches

900 MHz

1800 MHz

433 MHz200 MHz

70 MHz

1900 MHz


Vibrating RF MEMS


Basic Concept: Scaling Guitar StringsGuitar String

Guitar

Vibrating “A”String (110 Hz)Vibrating “A”

String (110 Hz)

High Q

110 Hz Freq.

Vib

. Am

plit

ud

e

Low Q

r

ro m

kfπ21

=

Freq. Equation:

Freq.

Stiffness

Mass

fo=8.5MHzQvac =8,000

Qair ~50

μMechanical Resonator

Performance:Lr=40.8μm

mr ~ 10-13 kgWr=8μm, hr=2μmd=1000Å, VP=5VPress.=70mTorr

[Bannon 1996]


Anchor Losses

Q = 15,000 at 92MHz

Fixed-Fixed Beam Resonator

GapAnchor AnchorElectrode

Problem: direct anchoring to the

substrate anchor radiation into the

substrate lower Q

Problem: direct anchoring to the

substrate anchor radiation into the

substrate lower Q

Solution: support at motionless nodal points

isolate resonator from anchors less

energy loss higher Q

Solution: support at motionless nodal points

isolate resonator from anchors less

energy loss higher Q

Lr

Free-Free Beam

Supporting Beams

λ/4

Anchor

Anchor

Elastic WaveRadiation

Q = 300 at 70MHz

Free-Free Beam Resonator


• Constructed in SiC material w/ 30 nm Al metallization for magnetomotive pickup

Lr

Wr

h

Frequency [GHz]

Mag

neto

mot

ive

Res

p. [n

V]

Design/Performance:Lr =1.1 μm, Wr =120 nm, h= 75 nm

fo=1.029 GHz, Q =500 @ 4K, vacuum

Design/Performance:Lr =1.1 μm, Wr =120 nm, h= 75 nm

fo=1.029 GHz, Q =500 @ 4K, vacuum

[Roukes, Zorman 2002]

Nanomechanical Vibrating Resonator


Scaling-Induced Performance Limitations

Mass Loading Noise

• Differences in rates of adsorption and desorption of contaminant molecules

mass fluctuationsfrequency fluctuations

Temperature Fluctuation Noise

• Absorption/emission of photons

temperature fluctuationsfrequency fluctuations

ContaminantMolecules

NanoresonatorMass ~10-17 kg

mk

2π1

of =

Photons

NanoresonatorVolume ~10-21 m3

• Problem: if dimensions too small phase noise significant!• Solution: operate under optimum pressure and temperature

[J. R. Vig, 1999]


Radial-Contour Mode Disk Resonator

VP

vi

Input Electrode

Output Electrode

io ωωο

ivoi

Q ~10,000Disk

Supporting Stem

Smaller mass higher freq. range and lower series Rx

Smaller mass higher freq. range and lower series Rx(e.g., mr = 10-13 kg)(e.g., mr = 10-13 kg)

Young’s Modulus

Density

Mass

Stiffness

RE

mkf

r

ro

121

⋅∝=ρπ

Frequency:

R

VP

C(t)

dtdCVi Po =

Note: If VP = 0V device off

Note: If VP = 0V device off


RF BPF

RF BPF

RF BPF

Multi-Band Wireless Handsets

Duplexer

90o0o

A/D

A/D

RXRF ChannelSelect PLL

I

Q

LPF

LPF

RXRF LO

I

QAGC

AGC

LNA

Duplexer RF BPF

LNAFrom TX

LNA

LNA

RF BPF

WCDMAWCDMA

CDMACDMA--20002000

DCS 1800DCS 1800

PCS 1900PCS 1900

LNA

Duplexer

LNA RF BPF

GSM 900GSM 900

CDMACDMA

From TX

From TX90o

0o

I

Q

Tank

÷ (N+1)/N XstalOsc

Antenna

Capacitively transduced

micromechanical resonators switch

themselves

Capacitively transduced

micromechanical resonators switch

themselves

No need for switches!

No need for switches!


-100-98-96-94-92-90-88-86-84

1507.4 1507.6 1507.8 1508 1508.2

1.51-GHz, Q=11,555 Nanocrystalline Diamond Disk μMechanical Resonator

• Impedance-mismatched stem for reduced anchor dissipation

• Operated in the 2nd radial-contour mode• Q ~11,555 (vacuum); Q ~10,100 (air)• Below: 20 μm diameter disk

PolysiliconElectrode R

Polysilicon Stem(Impedance Mismatched

to Diamond Disk)

GroundPlane

CVD DiamondμMechanical Disk

Resonator Frequency [MHz]

Mix

ed A

mpl

itude

[dB

]

Design/Performance:R=10μm, t=2.2μm, d=800Å, VP=7Vfo=1.51 GHz (2nd mode), Q=11,555

fo = 1.51 GHzQ = 11,555 (vac)Q = 10,100 (air)

[Wang, Butler, Nguyen MEMS’04]

Q = 10,100 (air)


Self-Aligned Fabrication Process

• Strategy: make stem misalignment impossible• Below:

successive film depositionssimultaneous definition of disk shape and stem location

Silicon Substrate

SiliconNitridePolysiliconOxide Polydiamond



• Below:define electrode-to-resonator gap spacing via sacrificial oxide sidewall spaceretch stem anchor

Silicon Substrate

SacrificialOxide

SidewallSpacer

Photoresist



• Below:deposit thick polysiliconpattern to define stem and electrodes

Silicon Substrate

Polysilicon



• Result: micromechanical disk with perfectly centered stem and nano-scale electrode-to-resonator gaps

Silicon Substrate

Sturdy PolysiliconElectrode (stronger

than previous metal)

Sturdy PolysiliconElectrode (stronger

than previous metal)

Tiny Gaps (50 nm gaps have been achieved)

Tiny Gaps (50 nm gaps have been achieved)

Micromechanical Disk Structure

Micromechanical Disk Structure

Self-Aligned Stem Perfectly Placed at Disk Center

Self-Aligned Stem Perfectly Placed at Disk Center


Output

Input Anchor

d = 80 nm• Right: zoom-in on the 80 nm gap achieved via the sacrificial sidewall spacer process

Tiny Lateral Transducer Gaps


•Freq.-Q product rising exponentially over the past years

1990 1995 2000 2005 2010

1015

109

1010

1011

1012

1013

1014

Year

Freq

uenc

y-Q

Prod

uct

silicon

diamond

silicon

silicon

silicon

silicon

silicon

fo = 1.51 GHzQ = 11,555

fo = 1.51 GHzQ = 11,555

silicon

μMechanical Resonator fo-Q Product

Intrinsic material Q limit nowhere

in sight?

Intrinsic material Q limit nowhere

in sight?


Micromechanical Resonator Oscillators


• Main Function: provide a stable output frequency• Difficulty: superposed noise degrades frequency stability

ωωο

ivoi

A

Frequency-SelectiveTank

SustainingAmplifier

ov

Ideal Sinusoid: ( ) ⎟⎠⎞⎜

⎝⎛= tofVotov π2sin

Real Sinusoid: ( ) ( ) ( )⎟⎠⎞⎜

⎝⎛⎟

⎠⎞⎜

⎝⎛ ++= ttoftVotov θπε 2sin

ωωο

ωωο=2π/TO

TO

Zero-Crossing Point

Tighter SpectrumTighter Spectrum

Oscillator: Need for High Q

Higher QHigher Q


Output

Input

Input

Output

Support Beams

Wine Glass Disk Resonator

R = 32 μm

Anchor

Anchor

Resonator DataR = 32 μm, h = 3 μmd = 80 nm, Vp = 3 V

Resonator DataR = 32 μm, h = 3 μmd = 80 nm, Vp = 3 V

-100

-80

-60

-40

61.325 61.375 61.425

fo = 61.37 MHzQ = 145,780

Frequency [MHz]

Unm

atch

ed T

rans

mis

sion

[dB

]

Polysilicon Wine-Glass Disk Resonator

[Y.-W. Lin, Nguyen, JSSC Dec. 04]

Compound Mode (2,1)


Phase Noise in Oscillators

• Single Sideband Phase Noise Density to Carrier Power Ratio in Oscillator, Lfm

Offset Frequency [Hz]

Phas

e N

oise

[dB

c/H

z]

100 1k 10k 100k10

-120

-100

-80

-60

-140

⇒ Carrier Frequency⇒ Offset Frequency⇒ Signal Power

of

mf

oP

•• High High QQreduces close-to-carrier phase noise

•• High High PPooreduces far-from-carrier phase noise

2

m

o

om fQ

fPkTfL ⎟

⎟⎠

⎞⎜⎜⎝

⎛

⋅⋅∝

f

Po


Wine Glass Disk Oscillator

Wine-Glass Disk Resonator (Q=48,000)

VDD = 1.65 V

VSS = -1.65V

M3M4

M1 M2

MRf

Vbias2

Vbias1

M11 M12 M13 M14

Vcm

M17M18

M16M15Output

Input

M5

Shunt-Shunt Feedback Tranresistance Amplifier

Common Mode Feedback Bias Circuit

VP

vi

io

Bond Wire ConnectionBond Wire Connection

MOS ResistorMOS

Resistor

VP=12V Rx=1.5kΩVP=12V Rx=1.5kΩ


OutputOutput Custom IC fabricated via TSMC 0.35μm process

Custom IC fabricated via TSMC 0.35μm process

InputInput

200 mV

20 ns

Frequency [MHz]

Pow

er [d

Bm

]

-100

-80

-60

-40

-20

0

61.05 61.1 61.15 61.2 61.25 61.3 61.35

Time & Freq. Domain Performance

Oscilloscope Waveform

Oscilloscope Waveform

Spectrum Analyzer Output

Spectrum Analyzer Output

[Y.-W. Lin, Nguyen, ISSCC’04]


-160-140-120-100

-80-60-40-20

0

1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06Offset Frequency [Hz]

Phas

e N

oise

[dB

c/H

z] 60 MHz, Wine-Glass Disk Oscillator

Down to 13 MHzFor Comparison

[Y.-W. Lin, Nguyen, JSSC’04]

1/f 3

Phase Noise Measurement

-130 dBc/Hz @ 1 kHz-130 dBc/Hz @ 1 kHz

-147 dBc/Hz-147 dBc/Hz

Nearly satisfies Global System for Mobile Communications (GSM)

phase noise specifications!

Nearly satisfies Global System for Mobile Communications (GSM)

phase noise specifications!Requires only 300 μW

and 150 x 150 μm2!Requires only 300 μW

and 150 x 150 μm2!

f

Po


Integrated Micromechanical Circuits


Micromechanical Filter Design Basics

RQ

vo

vi

RQ

VP

ω

xovi

ωo ω

xovi

ωo ω

vovi

ωo ω

vovi

ωo

Disk Resonator

Coupling Beam

Bridging Beam

Termination Resistor

Loss Pole

Loss Pole


-60

-50

-40

-30

-20

-10

0

8.7 8.9 9.1 9.3Frequency [MHz]

Tra

nsm

issi

on

[d

B]

Pin=-20dBm

In Out

VP

Sharper roll-off

Sharper roll-off

Loss PoleLoss Pole

Performance:fo=9MHz, BW=20kHz, PBW=0.2%

I.L.=2.79dB, Stop. Rej.=51dB20dB S.F.=1.95, 40dB S.F.=6.45

Performance:fo=9MHz, BW=20kHz, PBW=0.2%

I.L.=2.79dB, Stop. Rej.=51dB20dB S.F.=1.95, 40dB S.F.=6.45

Design:Lr=40μm

Wr=6.5μm hr=2μm

Lc=3.5μmLb=1.6μm VP=10.47VP=-5dBm

RQi=RQo=12kΩ

[S.-S. Li, Nguyen, FCS’05]

3CC 3λ/4 Bridged μMechanical Filter

[Li, et al., UFFCS’04]


Micromechanical Filter Circuit

1/krmr cr 1/krmr cr 1/krmr cr-1/ks -1/ks

1/ks

-1/ks -1/ks

1/ks

1/kb 1/kb

-1/kb

Co Co

1:ηe ηe:11:ηc 1:ηcηc:1 ηc:1

1:ηb ηb:1

λ/4

λ/4

3λ/4Input

Outputvi

RQ

RQ

vo

VP

Bridging BeamCoupling Beam

Resonator

ω

vovi


ω

vovi

Micromechanical Filter Circuit

1/krmr cr 1/krmr cr 1/krmr cr-1/ks -1/ks

1/ks

-1/ks -1/ks

1/ks

1/kb 1/kb

-1/kb

Co Co

1:ηe ηe:11:ηc 1:ηcηc:1 ηc:1

1:ηb ηb:1

λ/4

λ/4

3λ/4Input

Outputvi

RQ

RQ

vo

VP

Bridging BeamCoupling Beam

Resonator

All circuit element values determined

by CAD layout

All circuit element values determined

by CAD layout

Amenable to automated circuit

generation

Amenable to automated circuit

generation


-60

-50

-40

-30

-20

-10

0

8.7 8.9 9.1 9.3

High-Order Micromechanical Filter

[Wang, MEMS’97]

High-Order Micromechanical Filter

[Wang, MEMS’97]HF Micromech. Filter[Bannon, IEDM’96]

HF Micromech. Filter[Bannon, IEDM’96]

fo = 340kHzIL < 0.6dBRQ = 364kΩ

fo = 340kHzIL < 0.6dBRQ = 364kΩ

Frequency [MHz]

Tra

nsm

issi

on

[d

B]

Sharper roll-offs

Sharper roll-offs

Bridged μMech. Filter[S.-S. Li, UFFCS’2004]Bridged μMech. Filter[S.-S. Li, UFFCS’2004]

fo = 9.3MHzIL < 2.8dBRQ = 12kΩ

fo = 9.3MHzIL < 2.8dBRQ = 12kΩ

fo = 7.8 MHzIL < 2dBRQ = 14.7kΩ

fo = 7.8 MHzIL < 2dBRQ = 14.7kΩ

Loss poleLoss pole

• MEMS Filters excellent insertion loss• Problem: high impedance & poor power handling

Demo’ed Micromechanical Filters


Impedance Matching(Device Approach)


Solid Dielectric Capacitive Transducer

Antenna

r h

Gap = d

VP

Disk Electrode Electrode

Air Gap w/ ε = εo

Solid Dielectric w/ Solid Dielectric w/ εε = = εεrrεεoo in the Gapin the Gap

DiskΔGap κ timesPermittivity ε εr times

ΔGap κ timesPermittivity ε εr times

Rx εr2/κ times

( ) 222

4

221

hVd

Qk

rR

Po

rx εωπ

⋅=

377Ω

kr = 7,350,000 N/m

5kΩ

Mismatch!

ResonanceResonance

Opportunity: increase permittivity εsquare law reduction in Rx

Opportunity: increase permittivity εsquare law reduction in Rx


Output

InputAnchor

Tiny Lateral Solid-Dielectric Gaps

d = 80 nm

20nm 20nm Nitride GapNitride Gap

ElectrodeElectrode

Disk Disk ResonatorResonator

No small gap etch diffusion bottleneck

release step much faster than air gap case

No small gap etch diffusion bottleneck

release step much faster than air gap case

[Y.-W. Lin, C. Nguyen FCS’05]


Air- vs. Solid-Gap Comparison

-90

-80

-70

-60

-50

-40

-30

61.8 61.825 61.85 61.875 61.9

-130-120-110-100-90-80-70-60-50-40-30

61.75 61.85 61.95 62.05

60-MHz Wine-Glass Disk DataIn Vacuum, R = 32 µm, h = 3 µm

do = 80 nm (air gap)VP = 8 V, Pin = -10 dBm

fo = 61.927 MHz

Frequency [MHz]

Tran

smis

sion

[dB

] Q = 54,631

60-MHz Wine-Glass Disk DataIn Vacuum, = 32 µm, h = 3 µm

do = 20 nm (nitride gap) VP = 8 V, Pin = -30 dBm

fo = 61.855 MHz

Frequency [MHz]Tr

ansm

issi

on [d

B] Q = 36,814

Rx = 3.2 kΩRx = 42.67 kΩ

Rx 13X smallerRx 13X smaller

60-MHz WG Disk w/ Air Gap 60-MHz WG Disk w/ Solid Gap

Q is still very high even with solid gap

Q is still very high even with solid gap

Resonance frequency remains

virtually the same!

Resonance frequency remains

virtually the same!

Air GapAir Gap

Solid GapSolid Gap

[Y.-W. Lin, C. Nguyen FCS’05]


Benefit: Greatly Reduced DC-Bias

To achieve 50To achieve 50ΩΩ impedance, the DCimpedance, the DC--Bias voltage can be Bias voltage can be reduced from 147V to 0.91V using solid gap technologyreduced from 147V to 0.91V using solid gap technology

102030405060708090

100

0 20 40 60 80 100 120 140DC-Bias Voltage (V)

Mot

iona

l Res

ista

nce

(Ω) 80nm air

(ε = 1)

20nm nitride(ε = 7.8)

20nm HfO2(ε = 25)

20nm TiO2(ε = 80)

20nm BaSrTiO3(ε = 300)

147V11V 35V

3.5V0.91V

fo = 60 MHzQ = 40,000

fo = 60 MHzQ = 40,000

R = 32 μmh = 3 μm

R = 32 μmh = 3 μm

Assume Rx = 50Ωis required

Assume Rx = 50Ωis required


Freq

uenc

y [M

Hz]

Temperature [oC]

20 μm

Piezoelectric μMechanical Resonators

• Contour-mode, ring-shaped AlN Resonators• Driven laterally via the d31 coefficient

TCF ~ -24.7 ppm/ºCTCF ~ -24.7 ppm/ºC

• Freqs. up to 473 MHz (so far) determined by lateral dimensions!

• Q’s sufficient for pre-select filters

Tran

smis

sion

[dB

] -50

-60

-70

-80

-90474.25 484.25464.25

Frequency [MHz]

fo~473 MHz Q ~2,900 in air

Rx~80 Ω

fo~473 MHz Q ~2,900 in air

Rx~80 Ω

[Piazza, Pisano MEMS’05]


Impedance Matching(Mechanical Circuit Approach)


• Impedance matching needednot a new problem …

( ) 22

4

221

hVd

Qk

rR

Po

rx ⋅=

ωπ

μMechanical Disk Resonator

Antenna

377Ω

ResonanceResonance

kr = 7,350,000 N/m

5kΩ

Mismatch!

VDD

VSS

Off-ChipCapacitor

(2 pF)

MinimumSize

Inverter

2fFProgressively Larger Inverters

r h

Gap = d

VP

Issue: Impedance Matching


Impedance Reduction Via Arraying

RL

vo

io

Anchor

VPvi

Support BeamCoupling Beam

MotionalResistance

PowerHandling

Output Current

Freq.

λ/2

ElectrodePhasing Design

Peak Select

ElectrodePhasing Design

Peak Select

λ/2 DesignPeak Split

λ/2 DesignPeak Split


Support Beams Wine-GlassDisk

Anchor

InputElectrode

Coupling Beam

OutputElectrode

R = 32 μm

9-Wine-Glass Disk Composite Array

-110

-100

-90

-80

-70

-60

-50

-40

-30

61.8 61.85 61.9Frequency [MHz]

Tran

smis

sion

[dB

]

9-ResonatorQ = 118,900Rx = 2.56 kΩ

9-ResonatorQQ = 118,900= 118,900Rx = 2.56 kΩ

1-ResonatorQ = 161,000

Rx = 11.73 kΩ

1-ResonatorQQ = 161,000= 161,000

Rx = 11.73 kΩWine-glass disks

retain Q’s >100,000 even in large arrays!

Wine-glass disks retain Q’s >100,000

even in large arrays!

DataR = 32 μmh = 3 μm

d = 80 nmVP = 7 V

DataR = 32 μmh = 3 μm

d = 80 nmVP = 7 V


Wine Glass Disk Array Oscillator

VDD = 1.65 V

VSS = -1.65V

M3M4

M1 M2

MRf

Vbias2

Vbias1

M11 M12 M13 M14

Vcm

M17M18

M16M15Output

Input

M5

Shunt-Shunt Feedback Tranresistance Amplifier

Common Mode Feedback Bias Circuit

VP

vi

Bond Wire

Bond Wire

MOS ResistorMOS

Resistor

io

Wine-Glass Disk Array-Composite Resonator

Wine-Glass Disk Array-Composite Resonator

VP=7V Rx=2.5kΩ

Q = 118,900

VP=7V Rx=2.5kΩ

Q = 118,900


OutputOutputCustom IC fabricated via TSMC 0.35μm process

Custom IC fabricated via TSMC 0.35μm process

InputInput

GSM-Compliant Oscillator

[Y.-W. Lin, Nguyen, IEDM’05]

-160

-140

-120

-100

-80

-60

-40

-20

1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

Offset Frequency [Hz]

Phas

e N

oise

[dB

c/H

z]

9-Wine-Glass Disk ArrayQ = 118,900 , Rx = 2.56 kΩ9-Wine-Glass Disk ArrayQQ = 118,900 = 118,900 , Rx = 2.56 kΩ

9-WG Disk Array @ 62 MHz9-WG Disk Array @ 62 MHz

Single WG Disk @ 62 MHzSingle WG Disk @ 62 MHz

Down to 13 MHz

Down to 13 MHz

GSM specGSM spec

Satisfies Global System for Mobile Communications (GSM)


Satisfies Global System for Mobile Communications (GSM)


All made possible by mechanical circuit design!

All made possible by mechanical circuit design!


vi+

vi-

vo+

vo-

VP

VP

λ

λ/2

λ/4

λ/2

λ/4

Port1Port1

Port2Port2

Port3Port3

Port4Port4

λ

λ/2

λ/2

Filter CouplerCom. Array Couplers

Diff. Array Couplers

[Li, Nguyen Trans’07]

163-MHz Differential Disk-Array Filter


-75-70-65-60-55-50-45-40-35-30-25-20-15-10-50

162.6 162.8 163.0 163.2 163.4 163.6

TerminatedUn-terminated

Performancer=17μmh=3μmdo=80nmVP=14VP=-15dBmfo=163.126MHzQres=10,500Rx=977ΩBW=98.477kHzPBW=0.06% I.L.=2.43dB20dB S.F.=2.85RQ1=RQ2=1.6kΩRQ3=RQ4=1.4kΩ

Frequency [MHz]

Tra

nsm

issi

on

[d

B]

High Q & Low RXHigh Q & Low RX

RQ ~ 1.5kΩRQ ~ 1.5kΩ

RQ ~ 50ΩRQ ~ 50Ω

Measured Filter Freq. Characteristics


-120

-110

-100

-90

-80

-70

-60

-50

-40

0 50 100 150 200 250 300

Filter Measurement Over 300MHz Span

No Spurious ModesNo Spurious ModesFrequency [MHz]

Tra

nsm

issi

on

[d

B]

Performancer=17μmh=3μmdo=80nmVP=8VP=-15dBmfo=163.126MHzBW=98.477kHzPBW=0.06%


Wireless Phone

So Many Passive Components!



DiplexerDiplexer

925-960MHz RF SAW Filter925-960MHz

RF SAW Filter





RF Power Amplifier

RF Power Amplifier



3420-3840MHz VCO

3420-3840MHz VCO

90o0o

A/D

A/D

RF PLL

Diplexer

From TX

RF BPF

Mixer I

Mixer Q

LPF

LPF

RXRF LO

XstalOsc

I

Q

AGC

AGC

LNA

Antenna

Problem: high-Q passives pose a bottleneck against miniaturizationProblem: high-Q passives pose a bottleneck against miniaturizationNo longer a problem!No longer a problem!

Use as many high-Qpassives as desired!Use as many high-Qpassives as desired!

Seemingly limitless possibilities …

Seemingly limitless Seemingly limitless possibilities possibilities ……


RF Channel Selection


Motivation: Need for High Q

Antenna

Demodulation Electronics

The higher the Q of the Pre-

Select Filter the simpler the demodulation

electronics



electronics

Pre-SelectFilter in the GHz Range

Presently use resonators

with Q’s ~ 400


with Q’s ~ 400

Wireless Phone

Rec

eive

dPow

er

FrequencyωRF

DesiredSignal


Motivation: Need for Q’s > 10,000

Antenna




electronics



electronics



with Q’s ~ 400


with Q’s ~ 400

Wireless Phone

Rec

eive

dPow

er

FrequencyωRF

DesiredSignal

If can have resonator

Q’s > 10,000


Q’s > 10,000



Antenna




electronics



electronics



with Q’s ~ 400


with Q’s ~ 400


Q’s > 10,000


Q’s > 10,000

Wireless Phone

Non-Coherent FSK Detector?(Simple, Low Frequency, Low Power)

Front-End RF Channel Selection

Front-End RF Channel Selection

Rec

eive

dPow

er

FrequencyωRF

DesiredSignal

Substantial Savings in Cost and Battery PowerSubstantial Savings in

Cost and Battery Power



Antenna




electronics



electronics



with Q’s ~ 400


with Q’s ~ 400


Q’s > 10,000


Q’s > 10,000

Wireless Phone

Direct-Sampling A/D Converter Software-Defined Radio

Maximum Flexibility one circuit satisfies all

comm. standards

Maximum Flexibility one circuit satisfies all

comm. standardsFront-End RF

Channel SelectionFront-End RF

Channel Selection

Rec

eive

dPow

er

FrequencyωRF

DesiredSignal


RF Channel-Select Filter Bank

Bank of UHF μmechanical

filters

Bank of UHF μmechanical

filters

Switch filters on/off via

application and removal of dc-bias VP, controlled by

a decoder

Switch filters on/off via

application and removal of dc-bias VP, controlled by

a decoderTr

ansm

issi

on

Freq.

Tran

smis

sion

Freq.

Tran

smis

sion

Freq.

1 2 n3 4 5 6 7RF Channels

Remove all interferers!

Remove all interferers!


Conclusions

•• Vibrating RF MEMS have achievedVibrating RF MEMS have achievedQ’s >10,000 at GHz frequencies in sizes less than 20 μm in diameter and w/o the need for vacuum encapsulationTCf’s < -0.24 ppm/oC (better than quartz)aging at least on par with quartzcircuit-amenable characteristics VLSI potential

•• Time to turn our focus towards mechanical circuit design and Time to turn our focus towards mechanical circuit design and mechanical integrationmechanical integration

maximize, rather than minimize, use of high-Q componentse.g., RF channelizer paradigm-shift in wireless designeven deeper frequency domain computation

•• NeedNeed::automated design tools for LSI and highersingle-chip integrability with transistor circuitsmethods for frequency positioningcontinued scaling to nano-dimensions >10 GHz …

•• Beginnings of a revolution reminiscent of the IC revolution?Beginnings of a revolution reminiscent of the IC revolution?


• UC Berkeley:Clark Nguyen, Al Pisanocapacitive & AlN resonators

• Hughes Research:Randy Kubenaquartz resonators

• Cal Tech: Michael Roukesnanomechanical resonators

• Georgia Tech:Farrokh AyaziSOI resonators

• Stanford:Tom Kenny, Roger Howeepi/SOI, SiGe resonators

fo = 1.03 GHzQ = 500

fo = 1.03 GHzQ = 500

Growing Vibrating RF MEMS Research

fo = 473 MHzQ = 2,900Rx ~ 80Ω

fo = 473 MHzQ = 2,900Rx ~ 80Ω


Acknowledgments

• Former graduate students, especiallyProf. Jing Wang, now at the Univ. of South FloridaDr. Sheng-Shian Li, now at RF MicrodevicesDr. Yu-Wei Lin, now at Broadcom

• Much of the work shown was funded by grants from DARPA and by an NSF ERC in Wireless Integrated Microsystems

Integrated Micromechanical Circuits for RF Front-Ends · C. T.-C. Nguyen, “Integrated...

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Transcript of Integrated Micromechanical Circuits for RF Front-Ends · C. T.-C. Nguyen, “Integrated...