Chengjie Zuo

SSCS Catches Up with Its 2006–2011 Predoctoral Fellows

Mon, 07 Nov 2011 18:24:01 PST

Dual-Mode Resonator and Switchless Reconfigurable Oscillator Based on Piezoelectric AlN MEMS Technology

Chengjie Zuo et al. — Mon, 19 Sep 2011 12:26:51 PDT

For the first time, this work demonstrates a switchless dual-frequency (472 MHz and 1.94 GHz) reconfigurable CMOS oscillator using a single piezoelectric AlN microelectromechanical-systems resonator with coexisting S0 and S1 Lamb-wave modes of vibration. High performance (high quality factor Q and electromechanical coupling factor kt2 for a resonator and low phase noise for an oscillator) has been achieved for both the resonator and oscillator in terms of dual-mode operation. In particular, 1.94-GHz operation has the best phase noise performance at 1-MHz offset when compared with all previously reported CMOS oscillators that work at a similar frequency.

Switch-less Dual-frequency Reconfigurable CMOS Oscillator using One Single Piezoelectric AlN MEMS Resonator with Co-existing S0 and S1 Lamb-wave Modes

Chengjie Zuo et al. — Wed, 13 Jul 2011 11:40:06 PDT

For the first time, this work demonstrates a switch-less dual-frequency (472-MHz and 1.94-GHz) reconfigurable CMOS oscillator using a single piezoelectric AlN MEMS resonator with co-existing S0 and S1 Lamb-wave modes of vibration. High performances (high Q and kt2 for a resonator and low phase noise for an oscillator) have been achieved for both the resonator and oscillator in terms of dual-mode operation. Especially, the 1.94-GHz operation has the best phase noise performance when compared with all previously reported CMOS oscillators that work at a similar frequency.

Reconfigurable 4-Frequency CMOS Oscillator Based on AlN Contour-Mode MEMS Resonators

Matteo Rinaldi et al. — Thu, 02 Jun 2011 13:19:49 PDT

This paper reports on the first demonstration of a reconfigurable Complementary Metal Oxide Semiconductor (CMOS) oscillator based on MicroElectroMechanical System (MEMS) resonators operating at 4 different frequencies (268, 483, 690 and 785 MHz). A bank of multi-frequency switchable AlN Contour-Mode MEMS resonators (CMRs) were connected to a single CMOS oscillator circuit that can be configured to selectively operate in 4 different states with distinct oscillation frequencies. The phase noise (PN) of the reconfigurable oscillator was measured for each of the 4 different frequencies of operation showing values between -94 and -70 dBc/Hz at 1 KHz offset and PN floor values as low as -165 dBc/Hz at 1 MHz offset. Jitter values as low as 114 fs-rms (integrated 12 KHz - 20 MHz) and switching times as fast as 20 µs were measured. This first prototype represents a miniaturized solution (30X smaller) over commercially available Voltage Controlled SAW Oscillators (VCSOs) and potentially has the advantage of generating multiple stable frequencies without the need of cumbersome and power consuming phase locked loop (PLL) circuits.

Reconfigurable CMOS Oscillator Based on Multifrequency AlN Contour-Mode MEMS Resonators

Matteo Rinaldi et al. — Mon, 25 Apr 2011 10:18:48 PDT

This paper reports on the first demonstration of a reconfigurable complementary-metal-oxide-semiconductor (CMOS) oscillator based on microelectromechanical system (MEMS) resonators operating at four different frequencies (268, 483, 690, and 785 MHz). A bank of multifrequency switchable AlN contour-mode MEMS resonators was connected to a single CMOS oscillator circuit that can be configured to selectively operate in four different states with distinct oscillation frequencies. The phase noise (PN) of the reconfigurable oscillator was measured for each of the four different frequencies of operation, showing values between −94 and −70 dBc/Hz at a 1-kHz offset and PN floor values as low as −165 dBc/Hz at a 1-MHz offset. Jitter values as low as a 114-fs root mean square (integrated 12 kHz–20 MHz) and switching times as fast as 20 μs were measured. This first prototype represents a miniaturized solution (30 times smaller) over commercially available voltage-controlled surface-acoustic-wave oscillators and potentially has the advantage of generating multiple stable frequencies without the need of cumbersome and power-consuming phase-locked-loop circuits.

1.5-GHz CMOS Voltage-Controlled Oscillator Based On Thickness-Field-Excited Piezoelectric AlN Contour-Mode MEMS Resonators

Chengjie Zuo et al. — Tue, 02 Nov 2010 11:20:37 PDT

This paper reports on the first demonstration of a 1.5 GHz CMOS oscillator based on thickness-field-excited (TFE) piezoelectric AlN MEMS contour-mode resonators (CMRs). The measured phase noise is −85 dBc/Hz at 10 kHz offset frequency and −151 dBc/Hz at 1 MHz. This is the highest frequency MEMS oscillator ever reported using a laterally vibrating mechanical resonator. The high frequency operation has been enabled by optimizing the geometrical design and micro-fabrication process of TFE AlN CMRs, so that a low effective motional resistance around 50 Ω is achieved together with a high unloaded quality factor (Qu) approaching 2500 and simultaneously high kt2 up to 1.96%. A tunable-supply oscillator design is proposed for fine frequency tuning (or trimming) over a narrow bandwidth. The circuit design enables a novel GHz voltage-controlled oscillator (VCO) without the use of any low-Q tunable component. The 1.5 GHz VCO exhibits a 1500 ppm tuning range by a DC voltage change of 2.5 V. This technique can be utilized for fine frequency trimming and temperature compensation applications.

Single-Ended-to-Differential and Differential-to-Differential Channel-Select Filters Based on Piezoelectric AlN Contour-Mode MEMS Resonators

Chengjie Zuo et al. — Sun, 22 Aug 2010 12:46:10 PDT

This paper reports on the first demonstration of single-ended-to-differential and differential-to-differential (S2D and D2D) channel-select filters based on single-layer (SL) and dual-layer-stacked (DLS) AlN contour-mode MEMS resonators. The key filter performances in terms of insertion loss (as low as 1.4 dB), operating frequency (250-1280 MHz), and out-of-band rejection (up to 60 dB) constitute a significant advancement over all other state-of-the-art RF MEMS technologies. The fabrication process, namely stacking of two piezoelectric AlN layers (600 nm each) and three Pt electrode layers (100 nm each), is fully compatible with the previously demonstrated AlN RF MEMS switch process (also post-CMOS compatible), which makes it possible to implement multi-frequency switchable filter banks on a single chip. The S2D configuration is also able to combine the balun, filter, and impedance transformer functions in a single MEMS structure and only takes on a very small form factor (60×200 μm). These unique features will potentially revolutionize the field of RF and microwave IC design by enabling MEMS-IC co-design and the development of unconventional and low-power RF architectures.

GHz Range Nanoscaled AlN Contour-Mode Resonant Sensors (CMR-S) with Self-Sustained CMOS Oscillator

Matteo Rinaldi et al. — Sun, 13 Jun 2010 14:29:36 PDT

This 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.

Very High Frequency Channel-Select MEMS Filters Based on Self-Coupled Piezoelectric AlN Contour-Mode Resonators

Chengjie Zuo et al. — Thu, 03 Jun 2010 08:40:46 PDT

This paper reports experimental results on single-chip multi-frequency channel-select filters based on self-coupled piezoelectric aluminum nitride (AlN) contour-mode microelectromechanical (MEMS) resonators. Two-port AlN contour-mode resonators are connected in series and electrically coupled using their intrinsic capacitance to realize multi-frequency (94–271 MHz), narrow bandwidth (~0.2%), low insertion loss (~2.3 dB), high off-band rejection (~60 dB) and high linearity (IIP3 ~100 dBmV) channel-select filters on the same chip. This technology enables multi-frequency, high-performance and small-form-factor filter arrays and makes a single-chip multi-band reconfigurable radio frequency (RF) solution possible in the near future.

Multifrequency Pierce Oscillators Based on Piezoelectric AlN Contour-Mode MEMS Technology

Chengjie Zuo et al. — Thu, 03 Jun 2010 01:41:28 PDT

This paper reports on the first demonstration of multifrequency (176-, 222-, 307-, and 482-MHz) oscillators based on the piezoelectric AlN contour-mode microelectromechanical systems technology. All the oscillators show phase noise values between −88 and −68 dBc/Hz at 1-kHz offset frequency from the carriers and phase noise floor values as low as −160 dBc/Hz at 1-MHz offset. The same Pierce circuit design is employed to sustain oscillations at the four different frequencies; on the other hand, the oscillator core consumes 10 mW. The AlN resonators are currently wire bonded to the integrated circuit realized in the AMIS 0.5-μm 5-V complimentary metal-oxide-semiconductor process. Limits on phase noise and power consumption are discussed and compared with other competing technologies. This paper constitutes a substantial step forward toward the demonstration of a single-chip multifrequency reconfigurable timing solution that can be used in wireless communications and sensing applications.

Single-Ended-to-Differential and Differential-to-Differential Channel-Select Filters Based on Piezoelectric AlN Contour-Mode MEMS Resonators for Multi-Frequency Reconfigurable RF Transceivers

Chengjie Zuo — Tue, 01 Jun 2010 17:55:48 PDT

USTC: A Powerhouse of Talent

Fri, 30 Apr 2010 07:08:44 PDT

Power Handling and Related Frequency Scaling Advantages in Piezoelectric AlN Contour-Mode MEMS Resonators

Chengjie Zuo et al. — Tue, 16 Mar 2010 12:36:58 PDT

This paper reports on the analytical modeling and experimental verification of the mechanically-limited power handling and nonlinearity in piezoelectric aluminum nitride (AlN) contour-mode resonators (CMR) having different electrode configurations (thickness field excitation, lateral field excitation, one-port and two-port configurations) and operating at different frequencies (177-3047 MHz). Despite its simplicity, the one-dimensional analytical model fits the experimental behavior of AlN CMRs in terms of power handling capabilities. The model and experiment also confirm the advantage of scaling (i.e. miniaturizing) the AlN CMRs to higher frequencies at which higher critical power density can be more easily attained up to values in excess of 10 μW/μm3.

ss-DNA Functionalized Ultra-Thin-Film AlN Contour-Mode Resonators with Self-Sustained Oscillator for Volatile Organic Chemical Detection

Matteo Rinaldi et al. — Sat, 06 Feb 2010 21:52:07 PST

This paper reports on the design and experimental verification of a new class of nanoscale gravimetric sensors based on ultra-thin-film AlN Contour-Mode Resonant Sensor (CMR-S) functionalized with ss-DNA and connected to a chip-based self-sustaining oscillator loop (fabricated in the ON Semiconductor 0.5 μm CMOS process) for direct frequency read-out. The 220 MHz oscillator based on the ultra-thin AlN CMR-S exhibits an Allan Variance of ∼20 Hz for 100 ms gate time. The sensor affinity for the adsorption of volatile organic chemicals such as 2,6 dinitroluene (DNT, a simulant for explosive vapors) is enhanced by functionalizing the top gold electrode of the device with a thiol-terminated single stranded DNA sequence (Thiol - 5’ CTT CTG TCT TGA TGT TTG TCA AAC 3’) enabling the detection of concentrations as low as 1.5 part per billion (ppb).

Novel Electrode Configurations in Dual-Layer Stacked and Switchable AlN Contour-Mode Resonators for Low Impedance Filter Termination and Reduced Insertion Loss

Chengjie Zuo et al. — Tue, 26 Jan 2010 08:55:02 PST

This 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.

Super-High-Frequency Two-Port AlN Contour-Mode Resonators for RF Applications

Matteo Rinaldi et al. — Fri, 18 Dec 2009 13:00:41 PST

This paper reports on the design and experimental verification of a new class of thin-film (250 nm) super-high-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 contour-extensional 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, kt2, 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.

1.05-GHz CMOS Oscillator Based on Lateral-Field-Excited Piezoelectric AlN Contour-Mode MEMS Resonators

Chengjie Zuo et al. — Fri, 18 Dec 2009 12:41:11 PST

This 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.

Chengjie Zuo Receives SSCS Predoctoral Fellowship for 2009–2010

Mon, 16 Nov 2009 09:51:29 PST

Microscale inverse acoustic band gap structure in aluminum nitride

Nai-Kuei Kuo et al. — Sun, 11 Oct 2009 17:17:34 PDT

This work presents the design and demonstration of a microscale inverse acoustic band gap (IABG) structure in aluminum nitride (AlN) with a frequency stop band for bulk acoustic waves in the very high frequency range. Conversely to conventional microscale acoustic band gaps, the IABG is formed by a two-dimensional periodic array of unit cells consisting of a high acoustic velocity material cylinder surrounded by a low acoustic velocity medium. The periodic arrangement of the IABG array induces scattering of incident acoustic waves and generates a stop band, whose center frequency is primarily determined by the lattice constant of the unit cell and whose bandwidth depends on the cylinder radius, the film thickness, and the size of the tethers that support the cylinder. A wide band gap (>13% of the center frequency) is formed by the IABG even when thin AlN films are used. The experimental response of an IABG structure having a unit cell of 8.6 µm and an AlN film thickness of 2 µm confirms the existence of a frequency band gap between 185 MHz and 240 MHz.

Demonstration of Inverse Acoustic Band Gap Structures in AlN and Integration with Piezoelectric Contour Mode Transducers

Nai-Kuei Kuo et al. — Thu, 23 Jul 2009 07:39:29 PDT

This 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.