C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06 The Future of RF Microelectromechanical Systems (MEMS) Clark T.-C. Nguyen Dept. of Electrical Engineering & Computer Sciences University of California Berkeley, California 94720 E-mail : [email protected]BEARS’07 Feb.15, 2007
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The Future of RF Microelectromechanical Systems (MEMS)
The Future of RF Microelectromechanical Systems (MEMS). Clark T.-C. Nguyen Dept. of Electrical Engineering & Computer Sciences University of California Berkeley, California 94720 E-mail : [email protected] BEARS’07 Feb.15, 2007. Outline. - PowerPoint PPT Presentation
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C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
The Future of RF Microelectromechanical
Systems (MEMS)
Clark T.-C. Nguyen
Dept. of Electrical Engineering & Computer SciencesUniversity of California
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
Wireless Phone
Motivation: Miniaturization of RF Front-Ends
26-MHz Xstal Oscillator
26-MHz Xstal Oscillator
DiplexerDiplexer
925-960MHz RF SAW Filter
925-960MHz RF SAW Filter
1805-1880MHz RF SAW Filter
1805-1880MHz RF SAW Filter
897.517.5MHz RF SAW Filter
897.517.5MHz RF SAW Filter
RF Power Amplifier
RF Power Amplifier
Dual-Band Zero-IF Transistor Chip
Dual-Band Zero-IF Transistor Chip
3420-3840MHz VCO
3420-3840MHz VCO
Problem: high-Q passives pose a bottleneck against miniaturizationProblem: high-Q passives pose a bottleneck against miniaturization
90o
0o
A/D
A/D
RF PLL
Diplexer
From TX
RF BPF
Mixer I
Mixer Q
LPF
LPF
RXRF LO
Xstal Osc
I
Q
AGC
AGC
LNA
Antenna
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
Multi-Band Wireless Handsets
Duplexer
90o
0o
A/D
A/D
RXRF ChannelSelect PLL
I
Q
LPF
LPF
RXRF LO
I
QAGC
AGC
LNA
Duplexer RF BPF
LNA
From TX
LNA
LNA
RF BPF
RF BPF
RF BPF
WCDMAWCDMA
CDMA-2000CDMA-2000
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 Xstal Osc
Antenna
• The number of off-chip high-Q passives increases dramatically
• Need: on-chip high-Q passives
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
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 Q Tanks
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
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
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 200m for 1.6 GHz link 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
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
Vibrating RF MEMS
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
Substantial Savings in Cost and Battery PowerSubstantial Savings in
Cost and Battery Power
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
Motivation: Need for Q’s > 10,000
Antenna
Demodulation Electronics
The higher the Q of the Pre-
Select Filter the simpler the demodulation
electronics
The higher the Q of the Pre-
Select Filter the simpler the demodulation
electronics
Pre-SelectFilter in the GHz Range
Presently use resonators
with Q’s ~ 400
Presently use resonators
with Q’s ~ 400
If can have resonator
Q’s > 10,000
If can have resonator
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
dP
ower
FrequencyRF
DesiredSignal
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
RF Channel-Select Filter Bank
Bank of UHF mechanical
filters
Bank of UHF mechanical
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 decoder
Tra
nsm
iss
ion
Freq.
Tra
nsm
iss
ion
Freq.
Tra
nsm
iss
ion
Freq.
1 2 n3 4 5 6 7RF Channels
Remove all interferers!
Remove all interferers!
C. T.-C. Nguyen, “Towards MEMS-Based Receivers,” BWRC Winter Retreat, 1/(8-9)/06
Conclusions
• Vibrating RF MEMS have achievedVibrating RF MEMS have achievedQ’s >10,000 at GHz frequencies in sizes less than 20 m 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
• Probable evolution of products based on vibrating RF MEMS:Probable evolution of products based on vibrating RF MEMS: timing devices using micromechanical resonatorscommunication-grade frequency synthesizerssingle-chip of all needed high-Q passivesmechanical radio front-ends …
• In ResearchIn Research: Time to turn our focus towards mechanical circuit : Time to turn our focus towards mechanical circuit design and mechanical integrationdesign and mechanical integrationmaximize, rather than minimize, use of high-Q componentse.g., RF channelizer paradigm-shift in wireless designeven deeper frequency computation
• What’s possible with an unlimited supply of high-What’s possible with an unlimited supply of high-QQ passives? passives?