Simulation and fabrication of HF microelectromechanical bandpass filter

A high-frequency (HF) micromechanical bandpass filter fabricated using the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-process has been investigated in this study. The area of the filter is about 150×200 μm². The filter is composed of two resonators, which are joined by a coupling beam. Each resonator contains a membrane, four supported beams and two fixed electrodes, and the membrane is supported by four supported beams. The filter requires a post-process to etch the sacrificial layer, and to release the suspended structures. The post-process needs only one wet etching to etch silicon dioxide layer. The filter contains a sensing part and a driving part. When applying a driving voltage to the driving part, the sensing part generates a change in capacitance. The capacitance variation of the sensing part is converted into the output voltage by a sensing circuitry. Experiments show that the filter has a center frequency of about 39.6 MHz and a bandwidth of 330 kHz.     

一种新型微波开关的设计与实现

本文研究了一种新型的微波开关.利用震荡电路产生频率为50Hz(占空比为1%)的低频信号,低频信号通过施密特触发器得到10GHz的高频信号,然后通过高频振荡器发射微波束.利用波束障碍原理,当接收振荡器接收到的微波束经过滤波、放大、解调后,控制芯片(MSP430F149)对得到的幅值、低频频率、高频频率等参数进行判断,从而...     

自适应可变磁阻传感器放大器及其应用

LM1815是省略门电路的自适应传感放大器,适用于马 达控制。LM1815提供一次性脉冲输出,其前沿与反向过零 基准输入信号恰好一致。正常工作时,计时基准信号在外部 被处理（延迟）并且返回LM1815,然后逻辑输入可以用作 传送到输出驱动极的定时基准或处理信号。     

Microstrip PIN diode microwave switch

A possibility of creating narrow-band electrically controlled microwave breakers and switches with enhanced attenuation level in the blocking mode has been considered. The specified devices are based on the structure containing a short-circuited microstrip link with connected capacitor and the loop coupler, in the center of which is located a PIN diode.     

终端式MEMS微波功率传感器的设计与制作

A terminating type MEMS microwave power sensor based on the Seebeck effect and compatible with the GaAs MMIC process is presented. An electrothermal model is introduced to simulate the heat transfer behavior and temperature distribution. The sensor measured the microwave power from –20 to 20 dBm up to 20 GHz. The sensitivity of the sensor is 0.27 mV/mW at 20 GHz, and the input return loss is less than –26 dB over the entire experiment frequency range. In order to improve the sensitivity, four different types of coplanar waveguide （CPW） were designed and the sensitivity was significantly increased by about a factor of 2.     

Design, fabrication, and characterization of a germanium microwave transistor

This paper summarizes the design, fabrication, and characterization of a p-n-p planar epitaxial germanium transistor for use as an amplifier in the 1-to 4-GHz frequency range and as a high-speed switch. The analytical basis for the geometry and impurity profile arrived at in the development of this transistor is presented in conjunction with experimental measurements. It is shown that good agreement between experiment and theory can be achieved even in the 1-to 6-GHz frequency region when sufficient attention is given to the formulation of an adequate equivalent circuit. For example, the calculated fTof this germanium microwave transistor is 5.7 GHz, which compares to a typical measured value of 5.6 GHz. The measured maximum available gain of the better transistors is 13.4 dB at 1.3 GHz (the corresponding calculated value is 13.9 dB) with a 2.7-dB noise figure at the same frequency.     

Design and fabrication of a terminating type MEMS microwave power sensor

A terminating type MEMS microwave power sensor based on the Seebeck effect and compatible with the GaAs MMIC process is presented.An electrothermal model is introduced to simulate the heat transfer behavior and temperature distribution.The sensor measured the microwave power from-20 to 20 dBm up to 20 GHz.The sensitivity of the sensor is 0.27 mV/mW at 20 GHz.and the input retum loss is less than-26 dB over the entire experiment frequency range.In order to improve the sensitivity,four different types of coplanar waveguide(CPW) were designed and the sensitivity Was significantly increased by about a factor of 2.     

Modeling, design and fabrication of a freestanding nanoporous membrane

Nanoporous membranes are widely researched on many application fronts. One challenge for nanoporous membrane research is to provide mechanically stable designs due to inherently weak strength from diminished dimensions. We present a mathematical model that predicts the deflection behavior and strength of nanoporous membranes. Based on these mathematic predictions, we fabricated a nanoporous membrane based on a hierarchical design using microfabrication techniques. Direct force measurement with an atomic force microscope shows that the model accurately predicts the deflection behavior of the fabricated nanoporous membrane.     

Microwave switch: LAMPS (light-activated microwave photoconductive switch)

A new microwave switch, the light-activated microwave photoconductive switch consisting of a heterostructure photoconductive switch (HPCS) with a flip-chip bonded vertical-cavity surface-emitting laser is reported. An insertion loss of 0.17 dB at a laser power of 15 mW and an isolation of 25 dB were obtained at 1 GHz. Excellent linearity was obtained with second and third order intercepts measured at 960 MHz of SOI=115 dBm and TOI=65 dBm at 960 MHz, respectively.     

Electron beam and ion beam fabricated microwave switch

A combination of electron beam and ion beam techniques were used in conjunction with conventional planar technology to fabricate a junction field-effect microwave switch. A digital tape-controlled scanning electron beam was used to expose mask patterns in polymethyl methacrylate resist whose line widths (≤1 um) are inaccessible to conventional photolithography; ion beam sputtering was used to remove a thin gold undercoat from within the exposed patterns, thereby maintaining the good edge resolution; and ion implantation was used to dope the closely spaced interdigitated source and drain regions thus exposed by the preceding process steps in the gold contact mask.     

Problem of fabrication of diamond-based high-power microwave FETs

Numerical experiments are used to plan the development of diamond-based microwave FETs with an output power of 2.5 W per 1 mm of the gate width at a frequency of 15 GHz. A family of the I–V characteristics of the Schottky-barrier FET with gate length L _G = 50 nm and width W = 1 mm is calculated. Bases on analogy with a TGF2023-20 GaN HEMT, the topology of the high-power diamond transistor (parallel cells with gate widths W = 1.2 mm and 24 elementary gates per cell) is constructed.     

12dB微波薄膜衰减器的设计与制备

基于T型衰减网络结构设计并仿真了工作频率为DC~3GHz的微波薄膜衰减器,并采用磁控溅射法在BeO基片上制备了TaN微波薄膜衰减器。仿真结果表明,所设计的微波薄膜衰减器在DC~3GHz工作频率内,衰减量为12 dB,输入端口电压驻波比小于1.1。测试结果表明,所制备的微波薄膜衰减器在DC~3GHz工作频率内,衰减量为(12.0±0.5)dB。     

AlN多层共烧陶瓷微波外壳的设计与制作

使用Ansoft HFSS软件设计了一种微波多芯片组件(MCM)用陶瓷外壳,并采用AlN多层共烧陶瓷工艺制作了样品。微波输入输出(I/O)端子采用微带线直接穿墙形式,并与陶瓷外壳一体设计、制作。试验结果表明,在2～12 GHz内驻波比(VSWR)<1.3,测量漏率R1≤1×10–3Pa.cm3/s(He)。     

Fabrication and characterization of a microelectromechanical tunable capacitor

A micromechanical tunable capacitor fabricated using the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-process has been investigated in this study. The structure of the tunable capacitor consists of a membrane, supported beams, driving and sensing electrodes. The membrane is sustained by the supported beams. The tunable capacitor requires only one wet etching post-process to release the suspended structures. The post-process has the advantages of easy execution and low cost. The tunable capacitor contains a driving part and a sensing part. The sensing part generates a change in capacitance when applying a driving voltage to the driving part. Experimental results show that the tunable capacitor has a capacitance of 1.38 pF, a tuning range of 85% and a Q-factor of 40 at 100 MHz.     

InGaAs microwave switch transistors for phase shifter circuits

A new InGaAs insulated-gate FET (IGFET) with 1 μm gate length and three different gate widths has been designed, fabricated and characterized as switch devices for microwave control applications in phase shifter circuits. The devices employed a plasma deposited silicon dioxide gate insulator and had multiple air bridged source regions. The details of the DC current-voltage (I-V) characteristics and small signal S-parameter measurements up to 20 GHz are presented. The switch IGFET's had a drain saturation current density of 300 mA/mm gate width with breakdown voltages of higher than 35 V. An insertion loss of 1.0, 0.6, and 0.4 dB at 10 GHz and 1.4, 0.8, and 0.4 dB at 20 GHz have been measured for the 300, 600, and 1200 μm gate width IGFET's, respectively. Equivalent circuit models fitted to the measured S-parameters for IGFET's yielded on-state resistances from 10.7 to 3.3 Ω, off-state resistances from 734.4 to 186.8 R and off-state capacitances from 0.084 to 0.3 pF as the gate width is increased from 300 to 1200 μm The simulation results using IGFET models for the phase shifter circuits indicated a maximum phase error of 0.11°, 0.26°, and 0.479 with 0.74, 0.96, and 1.49 dB maximum insertion loss and greater than 33, 26, and 19 dB return loss for the 11.25°, 22.5°, and 45° phase bits, respectively, over the 9.5-10.5 GHz frequency band     

New reflection-type optoelectronic microwave switch for CW applications

The operation of a new type of optoelectronic switch is described. Using the principle of an optically controlled reflection coefficient, the capacitive effects of conventional gap-discontinuity devices are eliminated and the insertion loss can be made extremely low. This switch offers the possibility in the millimetre wave range.<>     

TaN微波功率薄膜匹配负载的设计及制备

基于有耗传输线理论设计了频率为DC-3GHz的TaN微波功率薄膜匹配负载,采用HFSS软件仿真了匹配负载的频率特性。根据设计仿真结果,采用反应磁控溅射和掩模图形化方法制备了TaN微波功率薄膜匹配负载样品,基片为6 mm×9 mm×1 mm的BeO陶瓷基片,TaN薄膜的直流电阻为50。结果表明,实验结果与仿真结果基本一致,在DC-3 GHz频率范围内,样品的电压驻波比(VSWR)都小于1.2。     

Modeling the visibility of breast malignancy by a microwave radiometer

A breast tumor is visible by a passive microwave radiometer if it changes the radiometric output of a healthy breast to an extent that overcomes the radiometric resolution for the given sensing antenna and integration time. We modeled breast temperature by the standard Pennes equation using thermal parameters found in the literature for normal and cancerous breast tissue. An apparent thermal volume and its dependence on blood perfusion have been estimated. The radiometric weighting function has been evaluated as a function of the size of a contacting antenna modeled as an aperture antenna. For comparison with the radiometric resolution, the difference signal between the outputs in the presence of a lesion and in its absence has been evaluated for different tumor sizes and depths. The results of the numerical analysis show that this difference signal depends on the average over-temperature in the lesion times the heating efficiency, given by the fraction of power delivered to the tumor when the antenna radiates onto the breast in active modality. A tumor of 6 mm (10 mm) diameter is visible by a 0.1 K radiometer and a 3 cm aperture antenna when it is not deeper than 1.2 cm (2.8 cm) under the assumption of ideal radiometer and antenna.     

Thermoelectric power sensor for microwave applications bycommercial CMOS fabrication

This work describes an implementation of a thermoelectric microwave power sensor fabricated through commercial CMOS process with additional maskless etching. The sensor combines micromachined coplanar waveguide and contact pads, a microwave termination which dissipates heat proportionally to input microwave power, and many aluminum-polysilicon thermocouples. The device was designed and fabricated in standard CMOS technology, including the appropriate superimposed dielectric openings for post-fabrication micromachining. By removing the bulk silicon located beneath the device through micromachining, thermal and electromagnetic losses are minimized. The sensor measures signal true RMS power in the frequency range up to 20 GHz with input power in the -30 dBm to +10 dBm range. Over this 40 dB dynamic range, output voltage versus input power is linear within less than ±0.16%. Automatic network analyzer data show an acceptable input return loss of less than -30 dB over the entire frequency range