A vertically integrated micromachined filter

A 10-GHz filter constructed of slot-coupled micromachined cavities in silicon is presented. The novel character of the filter lies in its structure, which consists of a microstrip feed to cavities via slot apertures and three vertically stacked slot-coupled cavities. The cavities are essentially reduced-height waveguide resonators. The measured results are presented and compared to a finite-element-method model. The simulated model has a bandwidth of 4% with an insertion loss of 0.9 dB at 10.02 GHz. The measured filter yields a 3.7% bandwidth with a deembedded insertion loss of 2.0 dB at 10.01 GHz. Various loss mechanisms are examined to explain the difference between simulated and measured insertion loss     

Transform domain adaptive linear phase filter

Describes a new adaptive linear-phase filter whose weights are updated by the normalized least-mean-square (LMS) algorithm in the transform domain. This algorithm provides a faster convergence rate compared with the time domain linear phase LMS algorithm. Various real-valued orthogonal transforms are investigated such as the discrete cosine transform (DCT), discrete Hartley transform (DHT), and power of two (PO2) transform, etc. By using the symmetry property of the transform matrix, an efficient implementation structure is proposed. A system identification example is presented to demonstrate its performance     

A micromachined silicon sieve electrode for nerve regenerationapplications

A micromachined silicon sieve electrode has been developed and fabricated to record from and stimulate axons/fibers of the peripheral nervous system by utilizing the nerve regeneration principle. The electrode consists of a 15-μm-thick silicon support rim, a 4-μm-thick diaphragm containing different size holes to allow nerve regeneration, thin-film iridium recording/stimulating sites, and an integrated silicon ribbon cable, all fabricated using boron etch-step and silicon micromachining techniques. The thin diaphragm is patterned using reactive ion etching to obtain different size holes with diameters as small as 1 μm and center-center spacings as small as 10 μm. The holes are surrounded by 100-200 μm² anodized iridium oxide sites, which can be used for both recording and stimulation. These sites have impedances of less than 100 kΩ @ 1 kHz and charge delivery capacities in the 4-6 mC/cm² range. The fabrication process is single-sided, has high yield, requires only five masks, and is compatible with integrated multilead silicon ribbon cables. The electrodes were implanted between the cut ends of peripheral taste fibers of rats (glossopharyngeal nerve), and axons functionally regenerated through holes, responding to chemical, mechanical, and thermal stimuli     

Vacuum-sealed silicon micromachined pressure sensors

Considerable progress in silicon pressure sensors has been made in recent years. This paper discusses three types of vacuum-sealed silicon micromachined pressure sensors that represent the present state of the art in this important area. The devices are a capacitive vacuum sensor, a surface-micromachined microdiaphragm pressure sensor, and a resonant pressure sensor. Vacuum sealing for these devices is accomplished using anodic bonding, films deposited using low-pressure chemical vapor deposition, and thermal out-diffusion of hydrogen, respectively. These sensors emphasize high sensitivity, small size, and excellent stability, respectively. The silicon-diaphragm vacuum sensor uses electrostatic force balancing to achieve a wide pressure measurement range     

Recent developments in micromachined silicon

This paper provides a review, directed at scientists and engineers concerned with microsystems technology, of advances in microelectromechanical systems (MEMS). The emphasis is on silicon technology, where the electrical properties of the material are exploited in circuitry and the mechanical properties are used in sensor and microstructure applications. Developments in surface micromachining are discussed, and applications in sensors, microelectronic devices, vacuum microanalysis systems, microfluidics, and optoelectronic subsystems are reviewed. Some emerging technologies are assessed and promising new research directions are identified     

FIR滤波器线性相位特性的研究

本文通过对滤波器的线性相位研究,介绍FIR滤波器的线性相位的4种特性,详细分析了FIR滤波器的线性相位的幅度特性,并在MATLAB下对FIR滤波器的4种特性进行模拟仿真实验,得到FIR数字滤波器的相位特性只取决于冲击响应的对称性.     

A micromachined silicon depth probe for multichannel neural recording

A process of making a new type of silicon depth-probe microelectrode array is described using a combination of plasma and wet etch. The plasma etch, which is done using a low temperature oxide (LTO) mask, enables probe thickness to be controlled over a range from 5 to 90 mu. Bending tests show that the probe's mechanical strength depends largely on shank thickness. More force can be applied to thicker shanks while thinner shanks are more flexible. One can then choose a thickness and corresponding mechanical strength using the process developed. The entire probe shaping process is performed only at low temperature, and thus is consistent with the standard CMOS fabrication. Using the probe in recording from rat's somatosensory cortex, we obtained four channel simultaneous recordings which showed clear independence among channels with a signal-to-noise ratio performance comparable with that obtained using other devices.     

A reduced-size silicon micromachined high-Q resonator at 5.7 GHz

This paper depicts the progress toward a novel high-quality-factor miniaturized resonator operating in the 5.6-5.8-GHz range. The design of the resonator is based on a micromachined cavity loaded with a high dielectric-constant material. Energy is coupled into the cavity from input and output microstrip lines via slots. Quality factors up to 640 are demonstrated on silicon planar structures with a volume of 177 mm/sup 3/. Further size reduction yields a volume of 24.5 mm/sup 3/ and quality factors ranging from 152 to 197, while keeping the resonator integration ability. Bonding techniques and the dielectric loss of the loading material are proven to be the limiting factors in achieving higher quality factors.     

A novel low-cost, high-efficiency micromachined silicon solar cell

This letter presents a new process for the fabrication of solar cells and modules from single crystal silicon wafers with substantially reduced silicon consumption and processing effort compared to conventional wafer-based cells. The technique of narrow trench etching in an alkaline solution is used to create a series of thin silicon strips extending vertically through the wafer. By turning the silicon strips on their side, a large increase in surface area is achieved. Individual cells fabricated using the new process have reached efficiencies up to 18.5% while a 575 cm/sup 2/ module incorporating a rear reflector and a cell surface coverage of 50% has displayed an efficiency of 12.3% under standard rating conditions. The technique has the potential to reduce silicon consumption by a factor of 10 compared to standard wafer-based silicon solar cells and, therefore, to dramatically reduce the dependence to the expensive silicon feedstock.     

Design considerations in micromachined silicon microphones

We present and compare the different designs of micromachined silicon condenser microphones. The aim is to develop the microphones with high sensitivity and low fabrication cost. Slotted and corrugated diaphragms have been designed and fabricated in order to increase the mechanical sensitivity of microphones. At the same time, we developed the fabrication process for the low stress or stress-free multilayers polysilicon used as the microphone diaphragms. To increase the microphone chip density on one wafer and avoid the sticking problem during the wet release process, a new process design using deep reactive ion etching is proposed, which is available in our laboratory.     

Microwave printed circuit linear phase selective filter design

Suspended-substrate printed circuit realization of microwave linear phase selective filter is presented. The transfer function that characterize the prototype filter has nonminimum phase nature. Suspended substrates are used because of the advantages they have over the microstips.     

On characterization of linear phase nonuniform filter banks

In this paper, a condition termed as linear phase condition (LPC), which ensures that the filters of a nonuniform filter bank are linear phase, is presented. It is observed that the proposed LPC is also applicable to the uniform filter bank case. Further, the utility of this LPC to find (i) necessary restrictions on the filters lengths, (ii) the number of symmetric and antisymmetric filters in the filter bank and (iii) filter bank decimation factors is also investigated. The results obtained for the different cases are also presented in the form of tables. These tables will facilitate the design of nonuniform filter bank by ruling out the non-solvable cases and by reducing the search space, thus saving the designers’ precious time.     

线性相位余弦调制滤波器组研究

图像子带编码要求滤波器组具有线性相位特性，非线性相位特性可对图像编译码带来影响。现研究了一种具有线性相位的最大抽取FIR余弦调制滤波器组，该滤波器组中每一个滤波器都具有线性相位，且由原型滤波器经余弦序列调制得到。经推导这种滤波器组可以设计成具有近似准确重构（NPR）特性或准确重构（PR）特性，文中分别给出了两种情况下滤波器组应满足的条件。通过对一幅图像的二维可分离滤波实验说明了当原型滤波器满足一定条件时滤波器组是准确重构的。     

Miniature micromachined Fabry-Perot interferometers in silicon

A new technique for the manufacture of miniature Fabry-Perot interferometers in silicon for use in the near-infra-red region is described. Tuning and parallelism control were achieved electrostatically, yielding low drive voltages and finesses exceeding 90 at 1.4 ?m. Such devices will prove useful for laser intracavity elements and wavelength demultiplexers in fibre telecommunication systems.     

A silicon micromachined device for use in blood cell deformabilitystudies

An application of silicon micromachining to the analysis of blood cell rheology is described. The system, based upon a micromachined flow cell, provides a specific measurement of each cell in a statistically significant population in terms of both flow velocity profile and an index of cell volume while the cells flow through an array of microchannels. The rationale, design, and fabrication of the silicon micromachined flow cell is discussed. Interrelated considerations determining the design of the associated fluidic, mechanical, imaging, and real-time image analysis subsystems are examined. Sample data comparing normal and iron deficiency anaemic blood are presented to illustrate the potential of this technique     

Long resonator micromachined tunable GaAs-AlAs Fabry-Perot filter

We present novel concepts for tunable optical filters. Long resonant cavities of about 30-/spl mu/m length have been realized with two-chip designs. GaAs technology has been applied to filters that are designed for the use in dense wavelength-division multiplexing (WDM) at wavelengths around 1550 nm. A finesse of 46.7, a full-width at half-maximum (FWHM) of 1.2 nm and electrostatic tuning over a range of 103 nm with an applied voltage of 35 V has been achieved. An alternative tuning concept that allows to tune the resonator length 4 /spl mu/m by heating Ni-Cr resistors placed on the suspending beams of a membrane with an applied voltage of 2.7 V has been realized.     

New linear phase QMF filter design for sub-band coding

A new technique for designing linear phase quadrature mirror filters (QMF) filters is proposed. These filters have the frequency responses of sharp and symmetrical transition characteristics, and the properties of perfect reconstruction and simple implementation.<>     

Substrate integrated waveguide (SIW) linear phase filter

A planar four-pole linear phase filter centered at 10GHz based on substrate integrated waveguide (SIW) is proposed. The filter is composed of four side-by-side horizontally oriented SIW cavities, which are coupled in turn by evanescent waveguide sections with three direct coupling and one cross coupling between the first and fourth SIW cavities. The SIW cavities are fed by microstrips through coupling slots. A curve-fitting technique is adopted to improve the efficiency of the design process. The measured results are presented and compared with the results simulated by a high-frequency structure simulator. Good agreement between the simulated and measured results is observed.     

无乘法的线性相位滤波器组的优化设计

提出了一种新的优化方法来设计系数为2的幂和(SOPOT)形式的线性相位完全重构(LPPR)滤波器组。其基本思想是将LPPR格型结构滤波器组中的格型系数直接表示成SOPOT形式，并将这些系数编码成个二进制码串，然后在一定的目标函数下利用遗传算法对这二进制码串进行优化。利用这种方法可以省去传统方法中首先设计无限精度系数的步骤，简化SOPOT型系数的LPPR滤波器组的设计过程。实验结果表明，该方法可以得到较好设计结果。