Over the past several decades, the technology of micro-electromechanical system（MEMS） has advanced. A clear need of miniaturization and integration of electronics components has had new solutions for the next generation of wireless communications. The aluminum nitride（AlN） MEMS contour-mode resonator（CMR）has emerged and become promising and competitive due to the advantages of the small size, high quality factor and frequency, low resistance, compatibility with integrated circuit（IC） technology, and the ability of integrating multi-frequency devices on a single chip. In this article, a comprehensive review of AlN MEMS CMR technology will be presented, including its basic working principle, main structures, fabrication processes, and methods of performance optimization. Among these, the deposition and etching process of the AlN film will be specially emphasized and recent advances in various performance optimization methods of the CMR will be given through specific examples which are mainly focused on temperature compensation and reducing anchor losses. This review will conclude with an assessment of the challenges and future trends of the CMR.
基于微机械系统（MEMS）圆盘谐振器工作时阻抗大、振荡频率高以及寄生电容大的特点,设计实现了一款用于驱动MEMS圆盘谐振器的宽带高增益、低噪声和低功耗跨阻放大器。该放大器引入低功耗宽带电流预放大和电流电压转换级输入技术,实现了宽带低功耗下低噪声性能。并结合改进型Cherry-Hooper反相器电压放大的电路结构以获得高增益带宽积,采用4～16译码控制电流、电压偏置技术,提高调试通过率及成品率。采用TSMC 0.18μm CMOS工艺流片后,测试结果表明,跨阻增益高达73 d BΩ,-3 d B带宽为163 MHz,功耗为21.6 m W,等效输入噪声电流谱密度为14 p A/Hz,芯片面积为1 538μm×680μm。
This paper presents an SOI（silicon on insulator） MEMS（micro-electro-mechanical systems） vibratory gyroscope that was fabricated using bulk micromachining processes.In the gyroscope architecture,a frame structure that nests the proof mass is used to decouple the drive motion and sense motion.This approach ensures that the drive motion is well aligned with the designed drive axis,and minimizes the actual drive motion component along the sense detection axis.The thickness of the structural layer of the device is 100μm,which induces a high elastic stiffness in the thickness direction,so it can suppress the high-order out-of-plane resonant modes to reduce deviation.In addition,the dynamics of the gyroscope indicate that higher driving mass brings about higher sensing displacements.The thick structural layer can improve the output of the device by offering a sufficient mass weight and large sensing capacitance.The preliminary test results of the vacuum packaged device under atmospheric pressure will be provided.The scale factor is 1.316×10^-4 V/（deg/s）,the scale factor nonlinearity and asymmetry are 1.87%and 0.36%,the zero-rate offset is 7.74×10^4 V,and the zero-rate stability is 404 deg/h,respectively.
A novel phase-locked loop( PLL)-based closed-loop driving circuit with ultra-low-noise trans-impedance amplifier( TIA) is proposed. The TIA is optimized to achieve ultra-low input-referred current noise. To track drive-mode resonant frequency and reduce frequency jitter of actuation voltage,a PLL-based driving technique is adopted. Implemented on printed circuit board( PCB),the proposed driving loop has successfully excited MEMS element into resonance,with a settling time of 3 s. The stable frequency and amplitude of TIA output voltage are 10.14 KHz and 800 mVPP,respectively. With sense-channel electronics,the gyroscope exhibits a scale factor of 0.04 mV/°/s and a bias instability of 57.6°/h,which demonstrates the feasibility of the proposed driving circuit.
A low-phase-noise CMOS voltage-controlled oscillator( VCO) with zero-bias scheme and multi-stage filtering is presented. Sharing ground w ith fully integrated loop filter,the PM OS-only VCO achieves a zero-bias scheme,w hich prevents tuning line noise from disturbing VCO output common-mode voltage and hence minimizes phase noise caused by nonlinear C-V characteristic of varactors. Top-biased current source is optimized by multi-stage filtering to reduce 1/f flicker and thermal noise. Fabricated in TSM C 180 nm CM OS process,the proposed VCO exhibits a measured oscillation frequency of 0.85 ~ 1.45 GHz,w ith a phase noise of-121.8 ^-131.3 dBc/Hz @ 1MHz offset over the w hole band. Pow er consumption is 3.8 ~ 6.3 mW from a 1.8 V supply.
This paper presents and analyzes a notch observed in MEMS （micro electric mechanical system） filter characterization using the difference method. The difference method takes advantage of the cancellation of parasitic feed-through, which could potentially obscure the relatively small motional signal and lead to failure in character- ization of the MEMS components. In this paper, typical clamped-clamped beam MEMS filters are fabricated and characterized with the difference method. Using the difference method a better performance is obtained but a notch is induced as a potential problem. Analysis is performed and reveals the mismatch of the two differential excitation signals in measurement circuit contributes to the notch. The relevant circuit design rule is also proposed to avoid the notch in the difference method.
