参考设计增强对移动WiMax的支持

SiGe半导体公司（SiGe Semiconductor）进一步扩大其RangeCharge产品线，推出三种无线射频（RF）前端模块。     

用于微波组件的LTCC Wilkinson功分器设计

基于LTCC工艺,设计了一种可用于微波组件的新型三维Wilkinson功分器,设计指标为:工作频带介于2.2～2.7GHz,插入损耗<0.5 dB,隔离度>20 dB,驻波比<1.30.使用HFSS软件为该功分器建立了模型并进行了仿真计算.仿真结果表明:该功分器在工作频带内的插入损耗<0.3 dB,隔离度>20dB,驻...     

Processing induced material interactions determining the reliability of LTCC multichip modules

Metals can exhibit dendritic short-circuit growth caused by electrochemical migration in conductor–insulator structures, which may result in failures and reliability problems in microcircuits. The classical model of electrochemical migration has been well known for several decades. This process is a transport of metal ions between two metallization stripes under bias through a continuous aqueous electrolyte. Due to the electrochemical deposition at the cathode, dendrites and dendrite-like deposits are formed. Ultimately, such a deposit can lead to a short circuit in the device and can cause catastrophic failure. Recent investigations have demonstrated that not only metallic components, but also oxides from the isolating layers can take part in the formation of migrated shorts, after a chemical reduction process. Material design aspects need to clarify the correlation between material composition, processing, chemical bonding state, and electrochemical migration failure rate in isolating compounds: this is the scope of the present study.     

Integrated polarization diversity front end optics

The integration of a polarization-diversity receiver front-end suitable for balanced detection has been realized by the hybrid combination of a 3-dB directional coupler and a thin-film polarization beam splitter (PBS) fabricated on silica-based waveguides. Insertion losses, excluding the intrinsic loss of the coupler, were 1 and 1.2 dB for TE- and TM-polarizations, respectively. The polarization cross talk was less than -23 dB     

Single-stage input-current-shaping technique withvoltage-doubler-rectifier front end

In this paper, a new single-stage input-current-shaping (S² ICS) technique that integrates the voltage-doubler-rectifier front end with a DC/DC output stage is introduced. Due to the voltage-doubler-rectifier front end, a reduction of line-current harmonics can be achieved with a higher conversion efficiency compared to the corresponding S²ICS circuit with the conventional wide-range full-bridge rectifier. The proposed technique requires energy-storage capacitors with the same total capacitance and with half of the voltage rating as in the conventional S²ICS counterpart, which reduces the size and cost of the power supply. The performance of the proposed technique is evaluated on a 450 W (5 V/90 A) experimental prototype circuit     

Thermal characterisation of power modules

This paper describes the thermal characterisation of power modules by means of a variable spreading angle model extended to multilayer structures. The model is used for thermal resistance calculation of assembled chips as a function of their size and according to the module construction and structure. This way of presenting thermal data is very useful to module manufacturers and users, allowing them to carry out an easy estimation of the thermal performance before building or ordering the module, so they can conform better to the application. Moreover, due to the closed form nature of the model, it can also be used for a quick estimation of the influence of the different parts and materials that constitute the module, in order to optimise its final structure. Experimental measurements carried on modules assembled with die of known sizes show good correlation with the calculations.     

A Ku-band integrated receiver front end

A Ku-band integrated receiver front end has been fabricated on 20-mil aluminum oxide substrates. The receiver consists of a balanced mixer and a Gunn oscillator within an area of 0.300/spl times/0.325 inch. The performance of both packaged and unpackaged microstripline receivers is described. Using external RF tuning, a noise figure of 9 dB at 18 GHz was obtained. A higher Q Gunn oscillator design is needed for more reliable single-frequency operation.     

LTCC高速热切速度控制方法研究

低温共烧陶瓷（LTCC）实现微波多芯片组件（MMCM）的一种理想组装技术．论述了制造微波多芯片组件的LTCC基板工艺,分析了LTCC基板生瓷材料在热切过程刀体运动流程以及其控制特点,研究了刀体在高速热切过程中的速度控制特点,提出了在确定结构下实现LTCC热切刀体的高精度和高速度控制方法,实验证明,在切割精度不受影响的情况下该方法提高了切割效率,减小了在高加减速情况下对机械系统造成的冲击。     

一种HFC网络管理系统前端控制器

本文介绍了一种由单片机控制的网络通信和管理系统。本系统可与ＰＣ机进行实时通信，并可对采集到的数据随进进行刷新存储。     

Optical front end for double-balanced homodyne receivers

An optical front end for double-balanced homodyne receiver is proposed. The device combines the function of a preamplifier, a 3-dB coupler, and a narrowband filter. A theoretical model is established and numerical results are presented. High gain and narrow bandwidth are predicted for this device     

Quasi-optical integrated antenna and receiver front end

A quasioptical receiver front end applicable to both microwave and millimeter-wave receiver arrays is presented. Two planar microwave integrated circuit (MIC) quasioptical receiver circuit designs that integrate a coupled slot antenna, a Schottky-diode balanced mixer, and a local oscillator on the same substrate are described. The even-mode/odd-mode characteristics of the coupled slotlines are used to achieve intrinsic RF/LO and RF/IF isolation. To demonstrate circuit feasibility, X-band scaled models of the circuit unit using a Gunn-diode oscillator on an Epsilam-10 substrate, and MESFET local oscillator on a R/T Duroid substrate were built and tested. Results of these tests are included     

Thermal impedance spectroscopy of power modules

In this paper, a method of thermal impedance spectroscopy for power modules is presented. This method enables a high resolution non-destructive analysis of the power module by means of electrical measurement and subsequent mathematical evaluation. The result provides a separation of partial thermal resistances corresponding material layers and facilitates a plausible estimation of geometrical dimensions of the power module package within the heat flow path. This method is applied for localization of failures during power cycling test.     

Design of compact stacked-patch antennas in LTCC multilayer packaging modules for wireless applications

A simple procedure for the design of compact stacked-patch antennas is presented based on LTCC multilayer packaging technology. The advantage of this topology is that only one parameter, i.e., the substrate thickness (or equivalently the number of LTCC layers), needs to be adjusted in order to achieve an optimized bandwidth performance. The validity of the new design strategy is verified through applying it to practical compact antenna design for several wireless communication bands, including ISM 2.4-GHz band, IEEE 802.11a 5.8-GHz, and LMDS 28-GHz band. It is shown that a 10-dB return-loss bandwidth of 7% can be achieved for the LTCC (/spl epsiv//sub r/=5.6) multilayer structure with a thickness of less than 0.03 wavelengths, which can be realized using a different number of laminated layers for different frequencies (e.g., three layers for the 28-GHz band).     

Thermal characterization of IGBT power modules

In this paper we report on experimental techniques for the thermal characterization of IGBT power modules. Three different systems have been used: the first one performs “in-time” characterization in order to control the most significant device parameters during normal operation or stress tests; the second one is for a complete and dynamic thermal characterization; finally, infrared optical analysis has been performed to validate the results.     

LTCC低温共烧陶瓷热切刀体控制探讨

对LTCC(低温共烧陶瓷)的热切割工艺过程进行论述,探讨了热切刀体和工作台的结构设计,分析了刀体和工作台的运动方式以及热切刀体的速度控制特点,提出了刀体加减速控制方法,成功实现了对LTCC热切刀体的高精度和高速度控制,实验证明,通过对刀体的运动进行曲线加减速控制,显著提高了切割效率、稳定性和一致性。     

Simple model for front and end contact resistances

The authors propose a simple model for contact resistance in the Berger and Kelvin structures which approximately accounts for finite substrate thickness in terms of closed-form expressions. The present model agrees with the transmission-line model for large contact resistivity, but deviates significantly in the other extreme.<>     

Transimpedance optical preamplifier having a common-collector front end

A simple PIN photodiode-bipolar transistor (PIN-BJT), direct-coupled, transimpedance, optical preamplifier suitable for fabrication in monolithic IC form is described. The preamplifier basically consists of a common-collector, common-emitter configuration with shunt feedback. Measurements indicate that the receiver is capable of a sensitivity of ?35.8 dBm at 140 Mbit/s for an error rate of 10?9.     

W波段超外差式辐射计射频前端的设计

针对毫米波辐射计接收前端探测灵敏度低、结构复杂、集成度低的问题,设计了一款用于W波段辐射计的射频前端组件.该组件工作于77～79 GHz频段,采用超外差一次变频接收体制,基于毫米波裸芯片及微带电路技术进行研制,组件集成了低噪声放大、本振源、下变频及中频放大等功能电路.在射频信号输入端,使用厚度为0.127 mm的石英基...     

无线收发前端小型化巴伦的研究

针对射频前端的小型化巴伦展开研究,在理论分析上,从变压器型巴伦的原理出发,将电磁场数值方法和微波网络理论相结合,将标准散射（S）参数和混合散射（S）参数相结合,提出了新颖的巴伦特性的理论研究方法;在实际应用上,利用高阻性硅基集成无源器件（Integrated Passive Device,IPD）技术,经过电磁仿真和优化,设计和制作了基于交叉耦合平面螺旋线结构的小型化变压器型巴伦.巴伦的尺寸仅为1.85 mm×1.6 mm,10 dB单端回波损耗带宽为2.07~2.80 GHz,频带内插入损耗小于0.98 dB,差分对幅度失配小于0.43 dB,相位失配小于3.8°,仿真结果得到了实验验证.