Spectrum Slicer:

Curtis Mayberry and David Giles

Narrowband Micromechanical Resonator Filters for RF Applications

Georgia Tech, October 8th, 2012ECE 6422—Interface IC Design for MEMS and

Sensors

*(Picture from [Piazza et al. 2007])

Problem Statement Motivation:

Rapid prototyping of RF Transceivers Efficient spectrum use Low cost, small area, fully integrated

RF Front-end Problem: RF Front-ends are

currently specially designed for a given application Considerable design effort for each

new design Conventional filters are not integrable

Objective: Design a reconfigurable RF front-end that can be used for rapid prototyping and development of RF Transceivers.

Specifically we are going to focus on the filtering and downconversion functions

Super-heterodyne Transceiver Architecture

Conventional Resonators Not integrable – large offchip size

Not tunable and only a single center frequency is allowed per die

Piezoelectric Crystals (Quartz widely used)

Other Materials including ceramic piezoelectric materials for low cost applications

Great Temp Stability – Low TCF(10 ppm/oC)

Low Cost

Rmot = 40-100 Ω

Low frequency f < 200 MHz Surface Accoustic Wave (SAW)

Rayleigh and longitudinal Propagation on the surface of a piezoelectric substrate

Good Temperature Stability

Good Q: up to 7000

Current Cell standards designed

assuming available SAW filtering

Technology

Thin Film Bulk Acoustic Resonators (FBAR) (Thickness-extensional)

[Shim et al. 2005] [Ueda et al. 2005] • Can have fairly high Qs (1000s)

and high electromechanical coupling (d33 coefficient)

• But—only 1 frequency per wafer• And thickness dimension cannot

be as accurately fabricated as lateral dimensions currently

• 1.94 GHz Tx filter based on FBARs

• Monolithic 7 FBAR ladder filter for a different Tx filter (1.9 GHz)

Capacitive Transduction

Require a charge pump [Pourkamali et al 2004] Disk Resonators

150 MHz Q-F product: 6.8*1012 (Vacuum) Q = 45700 (Vacuum), 25900 in air High motional Resistance: 43.3 kΩ

(Vacuum While reducing the capacitive gap

size reduces the motional resistance, the sensor output becomes nonlinear below 35nm

• Low Mechanical coupling• [Pourkamali et al 2007]• Sibar

– Advantages• High Q: 17300 (765 MHz, 5th

resonance mode)• Potential CMOS integration• Requires a charge pump• Reduced motional Resistance

with larger transduction area• High motional Resistance: 23.7

kΩ

Piezoelectric Transduction

• AlN-on-Silicon • 99.8 MHz fo

• Q = 3500• Rm = 35 O

[Tabrizian & Ayazi 2011] [Piazza et al. 2006]

• Al-AlN-Pt Stack

• 224 MHz fo

• Q = 2400• Rm = 56 O

[Nguyen et al. 2011]

• Capacitive/Piezo Combination

• Goal: High Q + Low Rm

• fo = 50 MHz• Q = 12,750

Bandpass Filters Using Resonators

[Zuo et al. 2010]

[Nguyen et al. 2006]

[Pourkamali et al. 2003]

[Verdu et al. 2006]

Our Solution

Channel Select filter bank enables reconfigurable, fully integrated direct downconversion.

NoiseFirst Stages most important

Filter ImplementationResonators• Piezoelectric-transduction for low motional

resistance• Lateral-mode for lithographically-defined resonance

frequency• AlN-on-Si/Diamond for Q enhancement (mass loading

versus decreased damping)• Sidewall-transduction—greater kt2

Electrical coupling—explore several possibilities Intrinsic capacitively-coupled—potential for small

device footprint Active cascading (amplifier stages between resonators)

—Q amplification may be necessary, but increased power dissipation and chip area may be too much

Ladder topology—for higher out-of-band rejection

Phase Noise

Noisy Oscillator waveform

ideal

noisy

Circuit SuggestionsLocal Oscillator

Challenge: Our frequency (~900 MHz) is approaching the bandwidth of this design (~900 MHz) at max gain

Noisy Oscillator Spectrum

ideal noisy

“Reciprocal Mixing”

Broadband: 960 MHz BW (MAX,880 @maxP)Low Power: 9.4 mW(1.5 v design)Low Phase Noise: -92 dBc/Hz and

Circuit Suggestions

Wideband LNA[Razavi 2010]50 MHZ to 10GHzNF = 2.9 to 5.7 dB

Large width to handle flicker noiseFor lower frequency bands

LNA

Mixer

Gilbert Cell

Local Oscillator

• Higher Bandwidth TIA Sustaining Amp• Add current amplifier pre-amp• Noise: Major contributing factor is M1 and M4 Current Noise:

Project 2 ObjectivesWe will design and simulate

1. At least two narrowband piezoelectric resonator-based filters, operating with center frequencies around 900 MHz

Good out-of-band rejection Low insertion loss Low motional impedance

2. A resonator-based local oscillator at 900 MHz

Low phase noise Good TCF Good drive capability Low Power

Sample DatasheetFilter Specifications Value Oscillator Specifications Valu

e

Center Frequency (MHz) 880/920

Frequency (MHz) 900

3dB Bandwidth (kHz) 1000 Power Dissipation (mW) 8

20dB Shape Factor 1.5 Phase Noise (1 kHz offset) (dBc/Hz)

-90

40dB Shape Factor 3 Phase Noise Floor (dBc/Hz) -140

Insertion Loss (dB) 4 Capacitive Drive Capability (pF)

2

Passband Ripple (dB) 0.5 Settling Time (ms) 2

Motional Impedance (Ohms)

200 Temperature Sensitivity (ppm/C)

20

• Small die area desired for both components <1mm2

• Atmospheric packaging is more economical but vacuum packaging enhances Q.

• Monolithic Integration for economic viability and use in RF FPAA

Simultaneously meeting Rm, IL, and SF specs will be challenging!!

References[1] B. Razavi, RF Microelectronics, Second Edition, Prentice Hall 2011.

[2] R. Aigner, “Innovative RF Filter Technologies: Gaurdrails for the Wireless Data Highway,” Microwave Product Digest. June 2007.

[3] S. Pourkamali, G. K. Ho, and F. Ayazi, “Low-impedance VHF and UHF capacitive silicon bulk acoustic wave resonators - Part I: Concept and Fabrication” IEEE Transactions on Electron Devices, May 2007, Vol. 54, No. 8, Aug. 2007, pp. 2017-2023.

[4] S. Pourkamali, G. K. Ho, and F. Ayazi, “Low-impedance VHF and UHF capacitive silicon bulk acoustic wave resonators - Part II: Measurement and Characterization,” IEEE Transactions on Electron Devices, Vol. 54, No. 8, Aug. 2007, pp. 2024-2030.

[5] Z. Hao, S. Pourkamali, and F. Ayazi, “VHF Single Crystal Silicon Elliptic Bulk-Mode Capacitive Disk Resonators; Part I: Design and Modeling,” IEEE Journal of Microelectromechanical Systems, Vol. 13, No. 6, Dec. 2004, pp. 1043-1053.

[6] S. Pourkamali, Z. Hao, and F. Ayazi, “VHF Single Crystal Silicon Elliptic Bulk-Mode Capacitive Disk Resonators; Part II: Implementation and Characterization,” IEEE Journal of Microelectromechanical Systems, Vol. 13, No. 6, Dec. 2004, pp. 1054-1062.

[7] H. Miri Lavassani, R. Abdolvand, and F. Ayazi, “A 500MHz Low Phase Noise AlN-on-Silicon Reference Oscillator,” Proc. IEEE Custom Integrated Circuits Conference (CICC 2007), Sept. 2007, pp. 599-602.

[8] H.M. Lavasani, W. Pan, B. Harrington, R. Abdolvand, and F. Ayazi, “A 76dBOhm, 1.7 GHz, 0.18um CMOS Tunable Transimpedance Amplifier Using Broadband Current Pre-Amplifier for High Frequency Lateral Micromechanical Oscillators,” IEEE International Solid State Circuits Conference (ISSCC 2010), San Francisco, CA, Jan. 2010, pp. 318-320

[9] B. Razavi, “Cognitive Radio Design Challenges and Techniques,” IEEE Journal of Solid-State Circuits, vol. 45, pp.1542-1553, Aug. 2010.

[10] J. Garrido, “Biosensors and Bioelectronics Lecture 10,”Walter Schottky Institut Center for Nanotechnology and Nanomaterials. http://www.wsi.tum.de/Portals/0/Media/Lectures/20082/98f31639-f453-466d-bbc2-a76a95d8dead/BiosensorsBioelectronics_lecture10.pdf

References (continued)[11] S. Pourkamali, R. Abdolvand, and F. Ayazi, “A 600kHz Electrically Coupled MEMS Bandpass Filter,” Proc. IEEE International Micro Electro Mechanical Systems Conference (MEMS‘03), Kyoto, Japan, Jan. 2003, pp. 702-705.

[12] R. Tabrizian and F. Ayazi, "Laterally Excited Silicon Bulk Acoustic Resonator with Sidewall AlN," International Conference on Solid-State Sensors, Acutators and Microsystems (Transducers), Beijing, China, June 2011.

[13] C. Zuo, N. Sinha, G. Piazza, “Very High Frequency Channel-Select MEMS Filters based on Self-Coupled Piezoelectric AlN Contour-Mode Resonators”, Sensors and Actuators, A Physical, vol. 160, no. 1-2, pp. 132-140, May 2010.

[14] G. Piazza, P.J. Stephanou, A.P. Pisano, “Piezoelectric Aluminum Nitride Vibrating Contour-Mode MEMS Resonators”, Journal of MicroElectroMechanical Systems, vol. 15, no.6, pp. 1406-1418, December 2006.

[15] Li-Wen Hung; Nguyen, C.T.-C.; , "Capacitive-piezoelectric AlN resonators with Q>12,000," 2011 IEEE 24th International Conference on Micro Electro Mechanical Systems (MEMS), pp.173-176, 23-27 Jan. 2011.

[16] Sheng-Shian Li; Yu-Wei Lin; Zeying Ren; C.T.-C. Nguyen; , "Disk-Array Design for Suppression of Unwanted Modes in Micromechanical Composite-Array Filters,". Istanbul. 19th IEEE International Conference on Micro Electro Mechanical Systems, 2006, pp.866-869, 2006.

[17] Dongha Shim; Yunkwon Park; Kuangwoo Nam; Seokchul Yun; Duckhwan Kim; Byeoungju Ha; Insang Song, "Ultra-miniature monolithic FBAR filters for wireless applications," Microwave Symposium Digest, 2005 IEEE MTT-S International, pp. 4 pp., 12-17 June 2005.

[18] Ueda, M.; Nishihara, T.; Tsutsumi, J.; Taniguchi, S.; Yokoyama, T.; Inoue, S.; Miyashita, T.; Satoh, Y.; , "High-Q resonators using FBAR/SAW technology and their applications," Microwave Symposium Digest, 2005 IEEE MTT-S International, pp. 4 pp., 12-17 June 2005.

[19] Gianluca Piazza, Philip J. Stephanou, Albert P. Pisano, One and two port piezoelectric higher order contour-mode MEMS resonators for mechanical signal processing, Solid-State Electronics, Volume 51, Issues 11–12, November–December 2007, Pages 1596-1608.