Zuo, Chengjie
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Publication Demonstration of Inverse Acoustic Band Gap Structures in AlN and Integration with Piezoelectric Contour Mode Transducers(2009-06-01) Kuo, Nai-Kuei; Zuo, Chengjie; Piazza, GianlucaThis paper presents the first design and demonstration of a novel inverse acoustic band gap (IABG) structure in aluminum nitride (AlN) and its direct integration with piezoelectric contour-mode transducers. The experimental results indicate that the IABG structure has a stop band from 185 MHz to 240 MHz and is centered around 219 MHz with maximum rejection of 30 dB. The ABG-induced phonon scattering causes a frequency band gap that prohibits the propagation of certain acoustic wavelengths. In this work, the IABG unit cell consists of a high acoustic velocity (V) center material, which is formed by 2-μm-thick AlN sandwiched by 200-nm-thick platinum (Pt) and is held by four thin tethers and surrounded by a low acoustic velocity material (air). This cell arrangement enlarges the frequency band gap and eases the requirements on the thickness (d) to lattice constant (a) ratio, which was imposed by previous ABG demonstration in the very high frequency range. The finite element method (FEM) analysis indicates that the IABG can produce a gap-to-midgap ratio of 13.5% even when the d/a ratio is as small as 0.23. This advantage further allows the direct integration of the IABG with high frequency bulk acoustic wave (BAW) transducers.Publication Novel Electrode Configurations in Dual-Layer Stacked and Switchable AlN Contour-Mode Resonators for Low Impedance Filter Termination and Reduced Insertion Loss(2010-01-01) Zuo, Chengjie; Sinha, Nipun; Piazza, GianlucaThis paper reports, for the first time, on the design and demonstration of two novel electrode configurations in dual-layer stacked Aluminum Nitride (AlN) piezoelectric contour-mode resonators to obtain low filter termination resistance (down to 300 Ω, which also results in better filter out-of-band rejection) and reduced insertion loss (IL as low as 1.6 dB) in multi-frequency (100 MHz – 1 GHz) AlN MEMS filters. The microfabrication process is fully compatible with the previously demonstrated AlN RF MEMS switches, which makes it possible to design and integrate multi-frequency switchable filter banks on a single chip.Publication Super-High-Frequency Two-Port AlN Contour-Mode Resonators for RF Applications(2010-01-01) Rinaldi, Matteo; Zuniga, Chiara; Zuo, Chengjie; Piazza, GianlucaThis paper reports on the design and experimental verification of a new class of thin-film (250 nm) superhigh- frequency laterally-vibrating piezoelectric microelectromechanical (MEMS) resonators suitable for the fabrication of narrow-band MEMS filters operating at frequencies above 3 GHz. The device dimensions have been opportunely scaled both in the lateral and vertical dimensions to excite a contourextensional mode of vibration in nanofeatures of an ultra-thin (250 nm) AlN film. In this first demonstration, 2-port resonators vibrating up to 4.5 GHz have been fabricated on the same die and attained electromechanical coupling, kt^2, in excess of 1.5%. These devices are employed to synthesize the highest frequency MEMS filter (3.7 GHz) based on AlN contour-mode resonator technology ever reported.Publication GHz Range Nanoscaled AlN Contour-Mode Resonant Sensors (CMR-S) with Self-Sustained CMOS Oscillator(2010-06-01) Rinaldi, Matteo; Zuniga, Chiara; Zuo, Chengjie; Piazza, GianlucaThis paper reports on the design and experimental verification of a new class of nanoscaled AlN Contour-Mode Resonant Sensors (CMR-S) for the detection of volatile organic chemicals (VOC) operating at frequencies above 1 GHz and connected to a chip-based CMOS oscillator circuit for direct frequency read-out. This work shows that by scaling the CMR-S to 250 nm in thickness and by operating at high frequencies (1 GHz) a limit of detection of ~35 zg/µm2 and a fast response time (<1 >ms) can be attained. In addition, the capability to detect concentrations of volatile organic compounds such as 2,6 dinitroluene (DNT) as low as 1.5 ppb (4.7 ag/µm2) is experimentally verified.Publication Demonstration of Inverse Acoustic Band Gap Structures in AlN and Integration with Piezoelectric Contour Mode Wideband Transducers(2009-04-01) Kuo, Nai-Kuei; Zuo, Chengjie; Piazza, GianlucaThis paper presents the first design and demonstration of a novel inverse acoustic band gap (IABG) structure in aluminum nitride (AlN) and its direct integration with contour-mode wideband transducers in the Very High Frequency (VHF) range. This design implements an efficient approach to co-fabricate in-plane AlN electro-acoustic transducers with bulk acoustic waves (BAWs) IABG arrays (10x10). The IABG unit cell consists of a cylindrical high acoustic velocity (V) media, which is held by four thin tethers, surrounded by a low acoustic velocity matrix (air). The center media is formed by 2-μm-thick AlN, which is sandwiched by 200-nm-thick top and bottom platinum (Pt) layers. The experimental results indicate that the designed IABG has a stop band from 185 MHz to 240 MHz and is centered at 218 MHz in the Γ-Χ direction. This demonstration not only confirms the existence of the frequency band gap in the IABG structure, but also opens possibilities for the integration of ABG structures with RF MEMS devices.Publication 1.05-GHz CMOS Oscillator Based on Lateral-Field-Excited Piezoelectric AlN Contour-Mode MEMS Resonators(2010-01-01) Zuo, Chengjie; Van der Spiegel, Jan; Piazza, GianlucaThis paper reports on the first demonstration of a 1.05-GHz microelectromechanical (MEMS) oscillator based on lateral-field-excited (LFE) piezoelectric AlN contour-mode resonators. The oscillator shows a phase noise level of −81 dBc/Hz at 1-kHz offset frequency and a phase noise floor of −146 dBc/Hz, which satisfies the global system for mobile communications (GSM) requirements for ultra-high frequency (UHF) local oscillators (LO). The circuit was fabricated in the AMI semiconductor (AMIS) 0.5-μm complementary metal-oxide-semiconductor (CMOS) process, with the oscillator core consuming only 3.5 mW DC power. The device overall performance has the best figure-of-merit (FoM) when compared with other gigahertz oscillators that are based on film bulk acoustic resonator (FBAR), surface acoustic wave (SAW), and CMOS on-chip inductor and capacitor (CMOS LC) technologies. A simple 2-mask process was used to fabricate the LFE AlN resonators operating between 843 MHz and 1.64 GHz with simultaneously high Q (up to 2,200) and kt2 (up to 1.2%). This process further relaxes manufacturing tolerances and improves yield. All these advantages make these devices suitable for post-CMOS integrated on-chip direct gigahertz frequency synthesis in reconfigurable multiband wireless communications.Publication Hybrid Ultra-Compact 4th Order Band-Pass Filters Based On Piezoelectric AlN Contour-Mode MEMS Resonators(2008-06-01) Zuo, Chengjie; Sinha, Nipun; Perez, Carlos R.; Mahameed, Rashed; Pisani, Marcelo B.; Piazza, GianlucaThis work reports on the design, fabrication and testing of a new class of hybrid (filter design using combined electrical and mechanical coupling techniques) ultra-compact (800×120 μm) 4th order band-pass filters based on piezoelectric Aluminum Nitride (AlN) contour-mode microelectromechanical (MEM) resonators. The demonstrated 110 MHz filter shows a low insertion loss of 5.2 dB in air, a high out-of-band rejection of 65 dB, a fractional bandwidth as high as 1.14% (hard to obtain when only conventional electrical coupling is used in the AlN contour-mode technology), and unprecedented 30 dB and 50 dB shape factors of 1.93 and 2.36, respectively. All these are achieved in an extremely small footprint and by using just half the space that any other 4th order filter would have taken. In terms of nonlinearities, the 110 MHz filter shows a 1 dB compression point higher than +63 dBmV and input third order intercept point (IIP3) values well beyond +153 dBmV. This new hybrid design represents a net improvement over the state of the art and constitutes a very promising solution for intermediate frequency (IF) filtering in many wireless communication systems.Publication AlN Contour-Mode Resonators for Narrow-Band Filters above 3 GHz(2009-04-20) Rinaldi, Matteo; Zuniga, Chiara; Zuo, Chengjie; Piazza, GianlucaThis paper reports on the design and experimental verification of a new class of thin-film (250 nm) super high frequency (SHF) laterally-vibrating piezoelectric microelectromechanical (MEMS) resonators suitable for the fabrication of narrow-band MEMS filters operating at frequencies above 3 GHz. The device dimensions have been opportunely scaled both in the lateral and vertical dimensions in order to excite a contour-extensional mode of vibration in nano features of an ultra-thin (250 nm) aluminum nitride (AlN) film. In this first demonstration two-port resonators vibrating up to 4.5 GHz were fabricated on the same die and attained electromechanical coupling, kt^2, in excess of 1.5 %. These devices were employed to synthesize the highest frequency ever reported MEMS filter (3.7 GHz) based on AlN contour-mode resonator (CMR) technology.Publication Channel-Select RF MEMS Filters Based On Self-Coupled A1N Contour-Mode Piezoelectric Resonators(2007-10-28) Zuo, Chengjie; Sinha, Nipun; Pisani, Marcelo B.; Perez, Carlos R.; Piazza, Gianluca; Mahameed, RashedThis paper reports experimental results on a new class of single-chip multi-frequency channel-select filters based on self-coupled aluminum nitride (A1N) contour-mode piezoelectric resonators. For the first time, two-port AlN contour-mode resonators are connected in series and electrically coupled using their intrinsic capacitance to form multi-frequency (94 – 271 MHz), narrow bandwidth (~0.3%), low insertion loss (~4 dB), high off-band rejection (~60 dB) and extremely linear (IIP3 ~110 dBm) channel-select filters. This novel technology enables multi-frequency, high-performance and small form factor filter arrays and makes a single-chip multi-band RF solution possible in the near future.