超宽带多功能数字化相控阵雷达系统技术

针对未来高威胁战场环境和复杂的作战使命要求,简要介绍了超宽带多功能数字化相控阵雷达系统技术,分析了影响其性能的几项主要技术,包括超宽带天线技术及波束控制技术、宽带信号波束形成实现技术、多功能多任务控制与调度技术、数字TR技术和DBF技术,以及它们的实现途径。     

A 9.1–10.7 GHz 10-W, 40-dB Gain Four-Stage PHEMT MMIC Power Amplifier

This letter presents a compact X-band high gain and high power four-stage AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT) monolithic microwave integrated circuit (MMIC) high power amplifier (PA). This amplifier is designed to fully match a 50-Omega input and output impedance. Based on 0.35-mum gate-length power PHEMT technology, this PA MMIC is fabricated on a 3-mil thick wafer. While operating under 8 V and 2700-mA dc bias condition, the characteristics of 40-dB small-signal gain, a 10-W continuous-wave saturation output power, and 33% power added efficiency at 9.7GHz can be achieved     

Cladding Layer Impedance Reduction to Improve Microwave Propagation Properties in p-i-n Waveguides

The cladding layer effect on microwave propagation properties of semiconductor p-i-n waveguides is investigated in this letter. Through the optical excitation in quantum wells of p-i-n waveguides, high-speed photocurrent is used to examine the microwave propagation. Two devices of p-i-n waveguides with different cladding layers are fabricated and measured, showing that a higher speed is found in the waveguide of wider cladding width. Verified by the microwave propagation properties, the higher speed is mainly attributed to lower microwave propagation loss due to the lower impedance in the wider cladding layer, suggesting this kind of structure can be applied to high-speed waveguide-based devices     

Radio resource management of heterogeneous services in mobile WiMAX systems [Radio Resource Management and Protocol Engineering for IEEE 802.16]

IEEE 802.16e, known as mobile WiMAX, has gained much attention recently for its capability to support high transmission rates in cellular environments and QoS for different applications. Beyond what the standard can define, in order to effectively support video streaming, VoIP, and data services, proprietary radio resource management, including multiconnection assignment, scheduling controls, and call admission controls, are essential. In this study we evaluate the downlink performance of a mobile WiMAX cellular system with different radio resource management, especially the scheduler for QoS control and the implementation of multiconnection for streaming applications     

A Fundamental 90-GHz CMOS VCO Using New Ring-Coupled Quad

A new circuit topology, named ring-coupled quad for millimeter-wave voltage controlled oscillator (VCO) design, is proposed. The proposed circuit topology provides higher open loop voltage gain than conventional cross-coupled pair. The layout of the proposed ring-coupled quad is fully symmetric without additional interconnection lines. A 90-GHz VCO using 90-nm CMOS process is implemented with this ring-coupled quad. This 90-GHz oscillator demonstrates a 2.5-GHz tuning range and higher than -20dBm output power. The proposed ring-coupled quad is suitable for the realization of high frequency VCOs     

Miniature CPW Parallel-Coupled Bandpass Filter Based on Inductive Loaded Coupled-Lines and Lumped-Element J-Inverters

This study presents a compact coplanar-waveguide (CPW) parallel-coupled bandpass filter (BPF) with good selectivity and stopband rejection. The inductive terminations are introduced to the conventional anti-parallel coupled-lines, and lumped-element J-inverters are employed, to achieve both size reduction and spurious suppression. Additionally, the inductive cross-coupling effect is introduced to obtain two transmission zeros to enhance the selectivity. Suitable equivalent-circuit model is also established as effective design tool. Specifically, this work demonstrates a compact cross-coupled fourth-order BPF in grounded-CPW configuration. Compared to the conventional filters, the proposed filters exhibit over 65% size reduction, improved selectivity, and wider stopbands up to four times the center frequency     

Embedded TFT nand-Type Nonvolatile Memory in Panel

A new NAND-type nonvolatile memory with a field-enhancing tip structure embedded in low-temperature polycrystalline silicon (LTPS) panel was demonstrated on a glass substrate for the first time. A thin-film transistor (TFT) metal-oxide-nitride-oxide-silicon (MONOS) device based on sequential lateral solidification crystallization with a fully depleted poly-Si channel, an oxide-nitride-oxide stack gate dielectric, and a metal gate is integrated into a NAND array. A NAND test array based on p-channel LTPS TFTs exhibits good cycling endurance and data retention properties and negligible program and read disturbance. These results strongly support the claim that this TFT-MONOS device is a promising candidate for use in embedded nonvolatile memory for system-on-panel and 3-D IC applications     

Defect Bragg Fiber With Low Loss for Broadband and Zero Dispersion Slow Light

Narrow bandwidth and large group velocity (v_g) dispersion are two fatal limitations of slow light in Bragg fibers. In this paper, by introducing a well-designed defect layer into the cladding of the Bragg fiber, the modal characteristics are modified by the coupling between the core mode and the defect mode. The defect location mainly determines the coupling strength and, thus, exerts a strong influence on v_g and dispersion. The defect thickness mainly determines the resonant wavelength of the defect waveguide and, thus, the wavelength where the modal coupling takes place. Consequently, the two limitations of the slow-light propagation in the Bragg fiber are overcome through proper optimization of the defect parameters. Around 1550 nm, a slow-light bandwidth up to 90 nm is achieved at an average v_g of c/5 (c is the light velocity in a vacuum) under N = 2, whereas an average v_g of c/10 is achieved with a bandwidth of 20 nm under N = 5. On the other hand, the slow-light propagation of v_g = 0.074c with both zero dispersion and zero dispersion slope is achieved, which is able to support applications requiring a subterahertz bandwidth of optical pulse. All of the fiber designs ensure sufficient low losses and good optical field distribution. The results are helpful in developing various Bragg-fiber-based slow-light devices.     

毛细管区带电泳法测定霍香正气胶囊中和厚朴酚的含量

目的:建立霍香正气胶囊中和厚朴酚含量测定的毛细管区带电泳(CZE)法.方法:采用甲醇溶解样品超声制备供试液;运行缓冲液为40mmol/L硼砂溶液,检测波长254nm.结果:和厚朴酚线性范围0.013-0.20mg/mL,r=0.9917(n=5),厚霍香正气胶囊中和厚朴酚的含量为0.1479mg/粒.结论:此方法快速简便,可用于评价霍香正气胶囊的质量.     

Novel transmitter of dark RZ signal based on external modulator

A novel transmitter to generate a dark RZ signal with tunable duty cycle and extinction ratio is proposed, by modifying the process of precoding, modulating and coding. A dark RZ signal is generated simply by using one dual-arm Mach-Zehnder LiNbO3 modulator. We demonstrate experimentally that this optical dark RZ signal can be directly measured by a conven- tional binary intensity modulation direct detection (IM-DD) receiver. When different values of duty cycles at 2.5 Gbit/s are adjusted, the experimental results show different BER curves and eye diagrams of the optical dark RZ signal.