MEMS双光纤位移声传感器设计与分析

提出了一种新型强度调制型光纤传感器的理论模型。该模型使用单模光纤,讨论了光在准直透镜中的传播规律,利用光学透镜的准直作用,即矩阵光学原理和高斯耦合理论实现光强调制。强度型光纤传感器采用微电机系统MEMS结构的压力振动膜片拾取振动位移,通过分析施加在膜片上压力的变化及膜片尺寸得到影响双光纤位移传感器灵敏度的相关参数。仿真结果表明:合理的选择参数可以使传感器的灵敏度在不增加结构复杂性的前提下较传统方法有103量级的提高。     

具有多运动自由度的新型多功能微镜

基于多层硅表面微加工技术,设计并制造了一种全新的微镜结构,它由底电极层、支撑层和镜面层构成．支撑层采用对称布置的双T型梁结构,能提供垂直方向的平动和绕两水平轴的转动,从而实现微镜对入射光的强度调制和相位调制功能．测试结果表明,微镜能获得最大2μｍ的平动范围,同时其绕两水平轴的转动角度分别为±2.3°和±1.45°．此外,通过进一步增大牺牲层的厚度,可以很容易地使微镜获得更大的变形范围．     

A CMOS low noise amplifier with integrated front-side micromachined inductor

The paper presents the design and characterization of a low noise amplifier (LNA) in a 0.18 μm CMOS process with a novel micromachined integrated stacked inductor. The inductor is released from the silicon substrate by a low-cost CMOS compatible dry front-side micromachining process that enables higher inductor quality factor and self-resonance frequency. The post-processed micromachined inductor is used in the matching network of a single stage cascode 4 GHz LNA to improve its RF performance. This study compares performance of the fabricated LNA prior to and after post-processing of the inductor. The measurement results show a 0.5 dB improvement in the minimum noise figure and a 1 dB increase in gain, while good input matching is maintained. These results show that the novel low-cost CMOS compatible front-side dry micromachining process reported here significantly improves performance and is very promising for System-On-Chip (SOC) applications.     

Miniature and tunable millimeter-wave lowpass filter with MEMS switch

In this paper, fully monolithic tunable millimeter-wave filters with tapped-line feedings are proposed using the CPW-based periodic structures with novel multiple-contact MEMS switches. Millimeter-wave low-pass filters were designed, fabricated, and tested. The cascaded CPW-based periodic structures, with low-pass intrinsic filtering characteristics, are reconfigured into a self-similar single unit cell by the operation of the novel multiple-contact MEMS switches with single actuation. The measured results of the reconfigurable low-pass filter show the 3-dB cutoff frequency change from 19 to 11 GHz with very small change in the average insertion loss from 1.3 to 1.9 dB. The chip size of the low-pass is 4.0 mm × 1.6 mm.     

New analogue inverse filters realised with current feedback op-amps

This article presents new configurations for realising analogue inverse lowpass, inverse bandpass, inverse highpass and inverse bandreject filters using commercially available current feedback op-amps (CFOA) with an accessible z-terminal (such as AD844). The workability of the proposed circuits has been confirmed by experimental results by employing AD844-type CFOAs.     

基于MEMS技术的微流体混合器及相关技术

介绍了基于MEMS技术的微流体混合器及相关技术,给出了各种微流体混合器的结构、原理和特点,同时对微管道中流体混合的仿真、实验技术以及微管道中微量流体混合程度的评价方法等作了概述。     

一种用于MEMS电容式加速度计的116dB动态范围CMOS读出电路

A high stability in-circuit reprogrammable technique control system for a capacitive MEMS accelerometer is presented. Modulation and demodulation are used to separate the signal from the low frequency noise. A low-noise low-offset charge integrator is employed in this circuit to implement a capacitance-to-voltage converter and minimize the noise and offset. The application-specific integrated circuit （ASIC） is fabricated in a 0.5 /μm one-ploy three-metal CMOS process. The measured results of the proposed circuit show that the noise floor of the ASIC is -116 dBV, the sensitivity of the accelerometer is 66 mV/g with a nonlinearity of 0.5%. The chip occupies 3.5×2.5 mm2 and the current is 3.5 mA.     

开关点电可调节的MEMS冲击加速度锁定开关

介绍了一种基于机电耦合原理的新型冲击加速度MEMS开关.此开关的阈值开关点可以通过偏置电压的改变进行调节设置,同时具有自锁定功能.文中分析了这种开关的准静态加速度静力学平衡条件和在阶跃冲击加速度输入情况下的响应特性,并通过CoventorWare软件模拟,得到悬臂梁型开关在各种加速度输入信号(阶跃、脉冲和半正弦)情况下的瞬态响应过程.开关的实际阈值范围为1000~5000g,响应速度小于60μs.采用MEMS技术制造开关,并通过冲击加速度测试验证了设计结果.     

开关点电可调节的MEMS冲击加速度锁定开关

介绍了一种基于机电耦合原理的新型冲击加速度MEMS开关.此开关的阈值开关点可以通过偏置电压的改变进行调节设置,同时具有自锁定功能.文中分析了这种开关的准静态加速度静力学平衡条件和在阶跃冲击加速度输入情况下的响应特性,并通过CoventorWare软件模拟,得到悬臂梁型开关在各种加速度输入信号(阶跃、脉冲和半正弦)情况下的瞬态响应过程.开关的实际阈值范围为1000~5000g,响应速度小于60μs.采用MEMS技术制造开关,并通过冲击加速度测试验证了设计结果.     

A novel system for displacement sensing, integrated on a plastic substrate

A micro system utilizing a novel sensing principle is presented in this paper. The determination of position is performed by exploiting the heat transfer between a heating source and a sensing device. The device itself consists of an array of temperature sensing elements, fabricated entirely on a plastic substrate. A specific fabrication technology was implemented which allows direct integration with read-out electronics and communication to the macro-world without the use of wire bonding. The fabricated sensing elements are temperature sensitive Pt thermistors. The device is able to detect both the position and the motion of a heating source by monitoring the induced resistance variation on the thermistor array. The heating source which performs a one-dimensional motion in a parallel plane to the temperature sensing array can be any element that can provide a highly localized temperature field. The system operation was characterized under both steady-state and dynamic conditions. In steady state mode the sensor exhibits a resolution of ±50 μm, while in dynamic conditions the device can detect signal frequencies up to 10 Hz.     

A dynamic collision model for improved over-range protection of cantilever-mass micromechanical accelerometers

A dynamic collision model is proposed and built to analyze over-range protection of cantilever beam-mass structured micro-accelerometers. The model encloses angular momentum of the seismic mass, squeeze-film air damping, inertial force and supporting force (acting at the cantilever-root) during the collision between the seismic mass and the over-range stopping bumpers. Based on angular momentum balance equation we obtain the relationship among the supporting force F, the collision time duration t and the rotation center c where the bumpers are located. In the best case of F=0 which means no supporting force acts on the cantilever, we find the optimal bumper location of c. The accelerometers have been fabricated with the over-range protection design according to the dynamic collision model. Experimental test shows that 5g measure-range accelerometers can endure 9000g acceleration and there is no sign of performance degradation, which well verified the dynamic collision model.     

Analysis of the Effect of the I/Q Base-Band Filter Mismatch in an OFDM Modem

In digital communication modems in which a very high rate system clock is used, it is necessary to use analog base-band shaping filters in the inphase (I) and quadrature (Q) paths of the modulator. However, this type of implementation inherently produces a mismatch of the I and Q paths. In the present paper, results of the analysis of the transmitter (TX) I/Q mismatch in an Orthogonal Frequency Division Multiplexing (OFDM) system with Differential Coherent Quadrature Phase Shift Keying (DQPSK) modulation is presented. Theoretical analysis shows that the Signal-to-Noise (SNR) degradation due to the I/Q mismatch can be represented by a mismatch transfer function on the basis of which one can compute the maximum affordable amplitude and phase mismatch of the TX filters transfer functions.     

A wide dynamic range CMOS image sensor with pulse-frequency-modulation and in-pixel amplification

This paper briefly examines the pros and cons of CMOS pulse-frequency-modulation (PFM) digital pixel sensors. A pulse-frequency-modulation digital pixel sensor with in-pixel amplification is proposed to improve the resolution of the pixel sensor at low illumination. The proposed PFM digital pixel sensor offers the characteristics of a reduced integration time when the level of illumination is low with the fill factor comparable to that of PFM digital pixel sensors without in-pixel amplification. The proposed digital image sensor has been designed in TSMC- 1.8 V CMOS technology and validated using Spectre from Cadence Design Systems with BSIM3V3 device models. Simulation results demonstrate that the dynamic range of the proposed PFM digital pixel sensor with in-pixel amplification is 20 dB larger as compared with that of PFM digital pixel sensors without in-pixel amplification. The increased dynamic range is obtained in the low illumination condition where PFM digital pixel sensors without in-pixel amplification cease the operation due to the low photo current.     

Design, fabrication and characterization of a bistable electromagnetic microrelay with large displacement

This paper reports the design, fabrication and characterization of a bistable electromagnetic microrelay based on non-silicon surface micromachining technology. It mainly consists of an integrated microcoil at bottom with a spacer, and a suspension spring with a permanent magnet on top. Bistable mechanism is realized by the adoption of the SmCo permanent magnet to hold the microrelay at latching position without current. Switching between two stable states is completed by the variation of current direction in the microcoil. The corresponding power consumption is 25 mJ. The fabrication processes of related components are presented. The test result shows that the bistable electromagnetic microrelay can work with low operation voltage pulse of 5 V. The output displacement is about 380 μm while the response time is about 4.96 ms. Besides, the test insertion loss is −0.02 dB and the isolation is −39.91 dB at 30 MHz.     

基于MEMS技术的射频移相器

微波与毫米波移相器是通讯和雷达应用上相控阵天线的基本单元，MEMS技术的引入提供了一个在移相器设计中用最小损耗的开关来大量减少移相器插入损耗的方法，该方法可以降低器件的功耗，改善插入损耗、隔离度、频带宽度等性能。相比于GaAs移相器，基于MEMS开关的射频移相器，无论是开关线型、分布式或是反射型，都有很好的RF性能。     

New type of analogue multiplier with wide dynamic range

For reasons which are discussed in this letter, the dynamic range of existing transconductance-type analogue multipliers falls short of that imposed by device limitations when they are used in a constant-output mode. It is shown that, by employing a new type of circuit in the feedback path of an operational amplifier, a dynamic range of 86 dB can be obtained over a control range of 30 dB with less than 0.25% departure from linearity.     

A technique for a substantial reduction of the quantization noise in the direct processing of delta-modulated signals

The quantization noise introduced by the direct arithmetic operations on delta modulated signals can be considerably reduced by a proposed technique. According to this technique, the arithmetic network of a digital filter is clocked at a rate higher than that of the delta modulation encoder. Thus, as it is proved, a considerable reduction of the maximum quantization error can be achieved. A simple network is properly used to restore the filter output rate to that of the delta modulation encoder. The experimental results prove that the output sequence quantization noise can be reduced so much that the remaining noise is very close to that of the input delta modulated signal of the filter.     

基于光子晶体光纤放大系统的皮秒方波产生

在光子晶体光纤飞秒激光放大系统中,利用液晶空间光调制器的调制特性,实现了对超短激光脉冲实时、可控的脉冲振幅整形,分析了大线性啁啾方波脉冲在放大过程中的频域和时域形状随泵浦功率的变化规律,在此基础上,通过液晶空间光调制器对主放大器前的脉冲频谱形状进行了预先调整,放大后获得了中心波长为1 031 nm,光谱宽度为13 nm,脉宽为15 ps的方波脉冲,证实了采用光谱优化后的飞秒脉冲作种子,可以较好地克服光子晶体光纤放大器增益不均引起的频谱形状的变化。     

基于滑膜阻尼的间接连接型音叉式微机械陀螺

以提高微机械陀螺性能为目的,设计了一种新颖的音又振动式微机械陀螺.该陀螺的特征在于:驱动和检测模态都是面内的,主要的空气阻尼是滑膜阻尼,使系统具有较低的能量损失和较高的Q值;对称的音叉式结构使检祆测电容加倍,并且由于中间结构的采用,对于加工误差具有较好的健壮性;采用驱动和检测方向具有较大刚度比的近似U型梁,使机械耦合大大降低.动力学分析的结果表明,该陀螺具有较高的稳定性和灵敏度.这不仅为获得高性能微机械陀螺提供了一种可行的设计方案,同时也为其它MEMS产品的设计提供了重要的参考价值.     

A New Two-Branch Amplification Architecture and its Application with Various Modulated Signals

This paper proposes a new two-branch amplification architecture that combines baseband signal decomposition with RF front-end optimization. In the proposed architecture, the filtered modulated signals are separated into two components that are then amplified independently and combined to regenerate an amplified version of the original signal. A branch with an efficient amplifier transmits a low-varying envelope signal that contains the main part of the information. Another branch amplifies the residual portion of the signal. The baseband decomposition and parameters of the RF part are optimized to find the configuration that gives the best power efficiency and linearity. For M-ary quadrature amplitude modulation （M-QAM） signals, this technique is limited in terms of power efficiency. However, for filtered continuous phase modulation （CPM） signals, especially for minimum shift keying （MSK） and Gaussian MSK （GMSK） signals, high power efficiency can be achieved with no significant impact on the overall linearity. The results show that this technique gives better performance than the single-ended ctass-B amplifier.