体声波滤波器理论及仿真

基于微加工技术制造的体声波滤波器品质因子高达数千,其性能已超过表面波滤波器,且可通过标准集成电路技术生产,将其用来替代通信系统中的传统射频滤波器,极具性能和价格优势。因此,该文以T型电路结构为基础,以固有衰减为出发点,推导体声波滤波器的通带和阻带频率特性。并以中心频率2.4 GHz、带宽36 MHz的体声波滤波器为例,作了详尽的分析和说明,并用Matlab软件仿真了其阻抗特性和传输特性。     

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。     

PZT材料在射频滤波器中的应用

锆钛酸铅 (PZT)材料有着优良的压电性能 ,其薄膜具有高机电耦合系数、高品质因数的特点 ,适合于制作低插损、大带宽的射频 (RF)滤波器。文中介绍了 RF体声波滤波器的原理、结构和 PZT的材料特性 ,探讨了PZT薄膜的制备、退火、刻蚀工艺的选择与优化 ,并在此基础上设计了应用 PZT薄膜的体声波滤波器 ,模拟了该器件的性能     

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.     

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。     

基于强度调制的光纤声传感器设计研究

在假设发送光纤出射端的光强分布为高斯分布的基础上,提出了一种新型强度调制型光纤声传感器模型。该模型根据单模光纤准直器的耦合特性理论,结合四周固支圆平微机电系统(MEMS)反射膜片,并使用GRIN lens光学透镜实现光强度的调制。仿真结果表明,通过选择合适的调制参数可使光纤声传感器的探测灵敏度较传统强度调制模型有数量级的提高。     

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.     

静电活塞式驱动的分立式微镜的快速仿真(英文)

用解析的方法对典型的基于SUMMIT工艺、静电活塞式驱动的分立式微镜进行了快速的静态与动态仿真,避免了有限元法的繁琐性。在微镜阵列变形时的孔径函数不能用解析表达式表示的情况下,应用MATLAB软件实现了快速傅里叶变换,得到了单色平面波经微镜阵列反射后的的远场衍射花样。     

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．     

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 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.     

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.     

基于MEMS工艺的硅基红外辐射源研制

利用微机电系统( MEMS)制造工艺制备出了一种硅基红外辐射源.该辐射源采用单晶硅为衬底,通过直流溅射沉积Pt/Ti薄膜,并利用深反应离子刻蚀与湿法腐蚀工艺制备隔离槽和释放支撑层.研究了支撑层厚度对红外辐射源辐射特性的影响.结果表明,随着支撑层厚度的减小,红外辐射源的调制驱动电压会降低.当支撑层厚度为1μm时,辐射源调...     

光的微电机系统在光通信网的应用

先简单表明未来的光通信网必然需要最合适的光器件。解释光的“微电机系统”有很好的发展前途。文中依次介绍光的微电机系统在光波长路由器、在光交叉连接和在光交换设备中的广泛应用。     

Series/Parallel Time-Multiplexed Switched-Capacitor Filters with Programmability Based on Non-Uniform Sampling

This paper presents an improved scheme for programmable time-multiplexed (TM) switched-capacitor (SC) filters. The proposed approach uses a novel sampling technique, which eliminates the need for resolution/area tradeoffs. The programmability of each processing channel is based on the use of non-uniform clock signals with noise-shaped sampling energy. No capacitor values are modified for programming frequency response parameters and, hence, the performance of the TM SC filter is not sacrificed for programmability. Such a sampling technique not only leads to an accurate frequency response control, but also allows the design procedures and the resulting SC circuit implementation to be simplified. A test-chip including a programmable second-order TM SC filter with a multiplexing order of four, which operates in series or in parallel mode, was fabricated in conventional CMOS technology. Measurement results demonstrate the effectiveness and versatility of the proposed technique.     

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.     

Switched-Current Filters by Component Simulation

This paper discusses the synthesis of switched-current filters from continuous-time prototypes by the simulation of components, particularly capacitors and transconductors in Transconductance-C filters. The obtained structures implement discrete-time versions of the prototype circuit using bilinear or Euler formulas. All the proposed structures work with doubled effective sampling rate (sampling the input and updating the output at each phase), make strict use of voltage-sampling switches and naturally admit two-phases nonoverlapping clocks.