Performance of silicon micromachined waveguide at W-band

Fabrication and measurement of low-loss micromachined waveguides developed in (001) silicon through wet anisotropic etching is detailed. Such waveguides are candidates for use in submillimetre-wave systems owing to their compatibility with both efficient micromachined horn antenna elements and planar-based circuitry     

140 GHz MEMS矩形波导滤波器

设计并实现了一种采用微机械制造(MEMS)技术加工的D波段矩形波导膜片滤波器.采用有限元仿真软件HFSS分析了滤波器内腔镀膜厚度、粗糙度以及感性膜片厚度对滤波器主要性能的影响.采用MEMS深刻蚀工艺(DRIE)成功加工出了滤波器主体结构.通过完成结构深刻蚀、金属电镀和键合等关键工艺,首次制造出了D波段MEMS波导滤波器.样品测试结果为插入损耗0.4～0.7 dB,中心频率(140±3)GHz,带外抑制为≥18 dB,样品主要技术指标与设计值符合.     

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.     

High-Q bulk micromachined silicon cavity resonator at Ka-band

A novel bulk silicon micromachining technique for fabricating millimetre-wave waveguide components is presented. This technique enables the formation of deep three-dimensional stacked structures of almost constant cross-section as well as post wafer-bonding metallisation that reduces the effects of air gaps and contact resistances. With these innovations it is possible to realise high-Q devices with low-cost fabrication. Simulated and measured results for a 30 GHz silicon cavity resonator are presented     

Characterization of a 680–760 GHz SIS waveguide mixer

A heterodyne waveguide receiver employing 1 µm² Nb superconducting tunnel junctions with on chip integrated tuning structures is characterized from 680–760 GHz. Several different types of integrated tuning structures are investigated. Lowest DSB receiver noise temperatures of 310 K at 709 GHz and 400 K at 720 GHz are measured. Analysis of the data shows that the loss of the superconducting tuning structures has a major influence on the overall receiver performance. A 25% reduction in receiver noise temperature is observed if the mixer is cooled from 4.2 K to 2 K, which we attribute to the reduced loss of the superconducting microstrip lines at lower temperatures. The calculated performance of the different tuning structures is shown to be in good agreement with the actual receiver noise measurements.     

640 Mbit/s waveguide transmitter at 38 GHz

The principle of a digital waveguide transmitter working at 38 GHz is given. A pulse-code-modulation simulator, with a bit rate of 640 Mbit/s, produces the modulation signal and also allows error-rate measurements. Typical switching times of the modulator are less than 500 ps. These results have been obtained by use of a varactor diode installed in a rectangular R band waveguide.     

Dielectric waveguide modulators at 95 GHz using LiNbO3

We describe electro-optic modulators at 95 GHz using LiNbO₃ in an H-guide configuration. We have observed 70% amplitude modulation at l KHz in a bridge configuration, corresponding to an induced phase shift of ±29°. The prospects for improved device performance will be discussed.     

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     

Experimental characterisation of 38 GHz micromachined GaAs receiver

The experimental characterisation of a 38 GHz micromachined GaAs receiver is presented. The structure monolithically integrates a double-folded slot antenna and a Schottky diode on the same GaAs thin membrane. The measurements demonstrate that this approach has the potential for innovative circuit architecture development.     

Characterization of rectangular waveguide with a pseudochiral /spl Omega/ slab

A mode matching approach has been employed for evaluating the matrix S of the section of rectangular waveguide with pseudochiral /spl Omega/ slab. Scattering characteristics for different localizations of the /spl Omega/ slab in the guide are predicted numerically and verified by measurements. Based on the numerical analysis, the scattering properties of the guides are discussed. Scattering parameters are next applied in an optimization procedure to extract constitutive parameters of the /spl Omega/ slab used in experiment.     

Scattering at an offset circular hole in a rectangular waveguide

A solution is given for the problem of scattering at an offset circular to rectangular junction and at a thick diaphragm, with an offset circular aperture, in a rectangular waveguide. The method used is mode matching for computing one discontinuity. The difficulty arising from the fact that the eigenmodes of the two waveguides are known in different coordinate systems is overcome by simple transformation for the evaluation of overlap integral between the eigenmodes of each waveguide. Experimental results validate this method     

Modes of crossed rectangular waveguide

The cutoff frequencies and modal fields of dually polarized crossed rectangular waveguide are calculated numerically and the cutoff frequencies verified experimentally. Symmetry arguments and group theory are used to explain mode degeneracies and mode splitting. The single mode bandwidth is 38 percent of center frequency for both polarizations when the guide dimensions are chosen appropriately. For applications where symmetric excitation is assured, bandwidths in excess of 2:1 can be obtained.     

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.     

Characterization and attenuation mechanism of CMOS-compatible micromachined edge-suspended coplanar waveguides on low-resistivity silicon substrate

This paper presents detailed characterization of a category of edge-suspended coplanar waveguides that were fabricated on low-resistivity silicon substrates using improved CMOS-compatible micromachining techniques. The edge-suspended structure is proposed to provide reduced substrate loss and strong mechanical support at the same time. It is revealed that, at radio or microwave frequencies, the electromagnetic waves are highly concentrated along the edges of the signal line. Removing the silicon underneath the edges of the signal line, along with the silicon between the signal and ground lines, can effectively reduce the substrate coupling and loss. The edge-suspended structure has been implemented by a combination of deep reactive ion etching and anisotropic wet etching. Compared to the conventional silicon-based coplanar waveguides, which show an insertion loss of 2.5dB/mm, the loss of edge-suspended coplanar waveguides with the same dimensions is reduced to as low as 0.5 dB/mm and a much reduced attenuation per wavelength (dB//spl lambda//sub g/) at 39 GHz. Most importantly, the edge-suspended coplanar waveguides feature strong mechanical support provided by the silicon remaining underneath the center of the signal line. The performance of the coplanar waveguides is evaluated by high-frequency measurement and full-wave electromagnetic (EM) simulation. In addition, the resistance, inductance, conductance, capacitance (RLGC) line parameters and the propagation constant of the coplanar waveguides (CPWs) were extracted and analyzed.     

MODFETs soar to 400 GHz

The operation of MODFETs (modulation-doped FETs) is explained. These devices now have switching delays under 5 ps, current-gain cutoff frequencies of about 250 GHz, and maximum oscillation frequencies in excess of 400 GHz. They also perform frequency division up to 26 GHz. Experimental ring oscillators, frequency dividers, static RAMs, and gate arrays are described. The microwave performance of MODFETs is discussed     

基于夹层氮化硅波导的可见-中红外超连续谱特性研究

提出一种低厚度氮化硅-蓝宝石-氮化硅夹层波导结构。利用其色散波辐射现象和中红外相位匹配条件,结合波导脉冲传输模型,讨论了夹层波导不同物理尺寸对相位匹配点和光谱展宽的影响,数值模拟获得了0.5~4 μm的超连续谱展宽,并且在-40 dB水平下具有更远中红外色散波产生。通过该模型,详细解释了非线性波导脉冲传输的潜在机制。理论模型分析表明,通过优化氮化硅及蓝宝石夹层的物理尺寸,进而改变相位匹配条件,可以在较宽的波长范围内控制色散波的位置。     

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.     

106 GHz low-loss beam waveguide

Measured data are presented from a 106 GHz, 85 m path, beam-waveguide system. The system comprises launching and collecting antennas of the offset feed design and two focusers, each in the form of two adjacent magnesium sheets. The total loss of the path, including antennas and focusers, is about 1.0 dB.     

20 GHz optical waveguide sampler

Picosecond pulses have been produced from the CW output of a He-Ne laser using a microwave-modulated optical waveguide interferometer formed in Ti-indiffused LiNbO3. An experimental frequency spectrum demonstrating 97 percent modulation is presented along with theoretical predictions for the spectral components of signals produced by both ideal nonideal devices. A device modulated with 1 W of power at 10 GHz exhibited a spectrum corresponding to a train of 19 ps FWHM pulses produced at a repetition rate of 20 GHz. Applications of the device in signal processing operations utilizing sampling and demultiplexing schemes are discussed.