自对准GaInP/GaAs HBT器件

利用发射极金属掩蔽进行内切腐蚀的方法研制成自对准InGaP/GaAs异质结双极晶体管 (HBT),其特征频率(ft)达到54GHz,最高振荡频率(fmax)达到71GHz,并且,这种方法工艺简单,成品率高.文中还对该结果进行了分析,提出了进一步提高频率特性的方法.     

S波段35W GaN功率MMIC

报道了一款采用两级拓扑结构的2～4 GHz宽带高功率单片微波功率放大器芯片.放大器采用了微带结构,并使用电抗匹配进行设计,重点在于宽带功率效率平坦化设计.经匹配优化后放大器在2～4 GHz整个频带内脉冲输出功率大于35 W,小信号增益达到22 dB,在2.4 GHz频点处峰值输出功率达到40 W,对应的功率附加效率为3...     

6～18 GHz宽带GaN功率放大器MMIC

报道了一款采用三级拓扑结构的6～18 GHz宽带单片微波功率放大器芯片.放大器采用了微带结构,并使用电抗匹配进行设计,减小输出匹配电路的损耗和提高效率.经匹配优化后放大器在6～18 GHz整个频带内脉冲输出功率大于6 W,小信号增益达到25 dB,在14 GHz频点处峰值输出功率达到10 w,对应的功率附加效率为21%...     

一种新型类Vicsek分形多频天线的设计

在Vicsek结构的分形理论基础上进行了改进, 提出了一种具有良好空间填充性和自相似特性的新型类Vicsek分形天线, 并在接地板上引入缺陷地结构(Defected Ground Structure, DGS)来改善频率、抑制谐波, 得到了可以运用在无线局域网(Wireless Local Area Networks, WLAN)、全球微波互联接入(Worldwide Interoperability For Microwave Access, WiMAX)以及C波段卫星通信的四个频段.天线的谐振频率分别为2.45 GHz、3.46 GHz、5.8 GHz和7 GHz, 相应带宽为0.2 GHz(2.37~2.57 GHz)、0.49 GHz(3.2~3.69 GHz)、0.75 GHz (5.52~6.27 GHz)和0.56 GHz(6.68~7.24 GHz), 增益最高达到4.89 dB.天线的小尺寸及全向性辐射特性表明该天线能很好地满足便携式多频段移动设备的要求.     

InP基长波长单片集成光接收前端的设计和制备

叙述了利用InP基长波长pin光探测器和异质结双极晶体管(HBT)单片集成实现光接收前端的设计和制备方法.pin光探测器和HBT采用共享层结构,这样的结构不仅性能优于堆叠层结构,而且制备工艺兼容.制备的HBT截止频率达到30GHz,pin光探测器的3dB带宽达到了15GHz,集成光接收前端的3dB带宽达到3GHz,跨阻放大倍数达到800.     

5~6GHz自适应线性化偏置的InGaP/GaAs HBT功率放大器

针对高质量无线局域网的传输需求,设计了一款工作在5~6 GHz的宽带磷化镓铟/砷化镓异质结双极型晶体管(InGaP/GaAs HBT)功率放大器芯片。针对HBT晶体管自热效应产生的非线性和电流不稳定现象,采用自适应线性化偏置技术,有效地解决了上述问题。针对射频系统的功耗问题,设计了改进的射频功率检测电路,以实现射频系统的自动增益控制,降低功耗。通过InGaP/GaAs HBT单片微波集成电路(MMIC)技术实现该功率放大器芯片。仿真结果表明,功放芯片的小信号增益达到32 dB;1 dB压缩点功率为28.5 dBm@5.5 GHz,功率附加效率PAE超过32%@5.5 GHz;输出功率为20 dBm时,IMD3低于-32 dBc。     

0.15μm GaN HEMT及其应用

报道了毫米波应用的0.15μm场板结构GaN HEMT。器件研制采用了76.2mm(3英寸)SiC衬底上外延生长的AlGaN/GaN异质结构材料,该材料由MOCVD技术生长并引入了掺Fe GaN缓冲层技术以提升器件击穿电压。器件栅脚和集成了场板的栅帽均由电子束光刻实现,并采用栅挖槽技术来控制器件夹断电压。研制的2×75μm栅宽GaN HEMT在24V工作电压、35GHz频率下的负载牵引测试结果显示其输出功率密度达到了4W/mm,对应的功率增益和功率附加效率分别为5dB和35%。采用该0.15μm GaN HEMT技术进行了Ka波段GaN功率MMIC的研制,所研制的功率MMIC在24V工作电压下脉冲工作时(100μs脉宽、10%占空比),29GHz频点处饱和功率达到了10.64W。     

基于变换采样的超宽带接收机设计

为了实现以较低的采样率对超宽带(UWB)脉冲信号进行采样以及在带宽和系统复杂度之间取得均衡,设计了一种基于变换采样的超宽带接收机系统.设计的接收机在AD芯片之前加入了跟踪保持放大器,提高了系统的模拟带宽(5GHz),通过采样时钟的较小延时实现了较高的等效采样率(8 GHz).主要用来接收带宽1 GHz以及以上的超宽带信号,利用VHDL进行编程,通过Chipscope抓取信号进行验证.测试表明,该系统能接收1 GHz以及以上带宽超宽带信号,达到了设计要求,可以用于超宽带通信与测距.     

3GHz低功耗低相位噪声的带自偏置电流源的LC压控振荡器

利用0.18μm CMOS工艺实现了一个全集成的工作于3GHz的低功耗、低相位噪声的压控振荡器,且带有自偏置电流源.通过对改进的电流源进行优化,在噪声与功耗之间达到了折中.该压控振荡器可工作于2.83至3.25GHz频段内,调谐范围达到13.8%.当工作于3.22GHz时,测得的相位噪声在1MHz频偏处为-111dBc/Hz.在1.8V电源电压下,核心模块消耗电流小于2mA.表明该电路适合5GHz的无线局域网接收机以及3.4至3.6GHz的全球微波互联接入(WiMAX)应用.     

体声波谐振式日盲紫外光传感器研究北大核心

提出了一种并联体声波谐振器(BAWR)与Ga_(2)O_(3)基MSM紫外传感器的新型高灵敏度传感器结构,即体声波谐振式日盲紫外光传感器(BAWR-UV Sensor)。设计并制备了MSM Ga_(2)O_(3)紫外传感器和BAWR传感器,将实测的光、暗S参数在仿真软件中封装为S1P数据模型代替MSM等效电路,用MBVD模型代替BAWR等效电路,通过并联两种结构建立了BAWR-UV仿真模型;采用ADS软件仿真了BAWR核心参数对BAWR-UV传感器灵敏度的影响,研究了提高灵敏度的设计方案。仿真结果表明,在0.5~4.5 GHz频率范围内,BAWR-UV的并联Q值越大,阻抗灵敏度越高,同时阻抗灵敏度随频率降低而增大,在并联谐振频率f_(p)=0.533 GHz时获得最佳阻抗灵敏度为100 kΩ/(μW/mm^(2));频率灵敏度随频率的升高而增大,在f_(p)=4.5 GHz时获得最佳频率灵敏度为1.4 MHz/(μW/mm^(2))。最后,开展了高灵敏度日盲紫外传感器的探索。     

太赫兹 InP HEMTs 的神经网络建模方法

包含新技术、新材料的非传统器件的不断涌现使现有的模型已不能完全表征THz 器件的特性。而采用神经网络 建模的方法,可极大地提高建模的效率和精确度,解决一系列传统模型所无法解决的问题,是一种新型的CAD 建模方法。 本文采用神经网络空间映射的方法,在传统的粗模型的基础上对输入信号进行有效地修正,从而得到适合太赫兹器件的 精确模型,器件的截止频率Ft 和最高振荡频率Fmax 分别为220GHz 和310GHz。模型在直流IV 和1-110GHz 范围内的S 参数与测试结果吻合较好,比传统粗模型的精度有了较大的提高。     

Heatsinking GaAs 4?18 GHz Gunn and IMPATT devices

A method for heatsinking high-power GaAs Gunn and IMPATT devices for the frequency range 4?18 GHz is described. The method is suitable for large-scale fabrication of devices, with high reproducibility and high quality. Typical microwave results are presented.     

Enhancement-mode AlGaN/GaN HEMTs fabricated by fluorine plasma treatment

The fabrication of enhancement-mode A1GaN/GaN HEMTs by fluorine plasma treatment on sapphire substrates is reported. A new method is used to fabricate devices with different fluorine plasma RF power treatments on one wafer to avoid differences between different wafers. The plasma-treated gate regions of devices treated with different fluorine plasma RF powers were separately opened by a step-and-repeat system. The properties of these devices are compared and analyzed. The devices with 150 W fluorine plasma treatment power and with 0.6μm gate-length exhibited a threshold voltage of 0.57 V, a maximum drain current of 501 mA/mm, a maximumtransconductance of 210 m S/mm, a current gain cutoff frequency of 19.4 GHz and a maximum oscillation frequency of 26 GHz. An excessive fluorine plasma treatment power of 250 W results in a small maximum drain current, which can be attributed to the implantation of fluorine plasma in the channel.     

微波半导体器件的计算机模拟

本文介绍半导体器件计算机模拟的物理模型和计算方法.以分析微波崩越二极管的大信号时间域模拟说明进行微波半导体计算机模拟的原理和过程,并给出对工作频率为40千兆赫的双漂移砷化镓崩越二极管进行计算机模拟的计算结果.     

High-performance oscillators and power combiners with InP Gunn devices at 260-330 GHz

InP Gunn devices with graded doping profiles were evaluated for second-harmonic power extraction above 260 GHz. The best devices generated radio frequency(RF) output power levels of 3.9 mW at 275 GHz, 4.8 mW at 282 GHz, 3.7 mW at 297 GHz, 1.6 mW at 329 GHz, and 0.7 mW at 333 GHz with corresponding dc-to-RF conversion efficiencies of 0.24%, 0.31%, 0.32%, 0.19%, and 0.07%. The highest observed second-harmonic frequency was 345 GHz. Two devices each in an in-line power combining circuit generated 6.1 mW at 285 GHz and 2.7 mW at 316 GHz with combining efficiencies of more than 65%.     

真空电子器件在100GHz以上频域的应用

太赫兹（THz）技术发展受到特别的关注,本文重点讨论了真空电子器件在100GHz以上频率几个大气窗口的应用,100GHz和220GHz是未来10年可能形成装备的频率,应当重视这些频率真空电子器件的预先研究。     

Performance Evaluation and Equivalent Model of Silicon Interconnects for Fully-Encapsulated RF MEMS Devices

This paper aims to demonstrate the utility of silicon interconnects for radio-frequency (RF) microelectromechanical system (MEMS) devices that are packaged using a wafer-scale encapsulation process. Design and fabrication steps for the packaged interconnects are described. Measurement results show that encapsulated devices can be operated at frequencies up to 6 GHz with less than 1 dB insertion loss from the through-package silicon interconnects. This paper also describes a simple and accurate lumped-element model for simulating the performance of packaged silicon interconnects. The model is verified with S-parameter measurements from 50 MHz to 6 GHz. The modeling method and extracted values are intended to aid in the design and simulation of RF MEMS devices packaged using this technology.      

Millimeter-wave high-power 0.25-/spl mu/m gate-length AlGaN/GaN HEMTs on SiC substrates

Reports on the CW power performance at 20 and 30 GHz of 0.25 /spl mu/m /spl times/ 100 /spl mu/m AlGaN/GaN high electron mobility transistors (HEMTs) grown by MOCVD on semi-insulating SiC substrates. The devices exhibited current density of 1300 mA/mm, peak dc extrinsic transconductance of 275 mS/mm, unity current gain cutoff (f/sub T/) of 65 GHz, and maximum frequency of oscillation (f/sub max/) of 110 GHz. Saturated output power at 20 GHz was 6.4 W/mm with 16% power added efficiency (PAE), and output power at 1-dB compression at 30 GHz was 4.0 W/mm with 20% PAE. This is the highest power reported for 0.25-/spl mu/m gate-length devices at 20 GHz, and the 30 GHz results represent the highest frequency power data published to date on GaN-based devices.     

Q and V band power InGaAs MESFETs

Excellent power performance at 44 and 60 GHz demonstrated by 0.25 mu m gate InGaAs MESFETs is reported. From small-signal S-parameter measurements, these devices typically have extrinsic f/sub t/ greater than 100 GHz. At 1 dB compression point, a 150 mu m wide MESFET shows a power added efficiency of 33% with an output power of 60.8 mW (0.43 W/mm) at 44 GHz. For 200 mu m wide devices, the power added efficiency was measured to be 19% with an output power of 82 mW (0.41 W/mm) at 60 GHz. These results indicate that InGaAs MESFETs are viable millimetre-wave power devices.<>     

50-110 GHz Gunn diodes using molecular beam epitaxy

Millimeterwave Gunn-oscillators have for the first time been fabricated using gallium arsenide grown by molecular beam epitaxy. Material produced by this new method of epitaxy has yielded c.w. integral heat sink oscillators with up to 20 mW of r.f. power at 90 GHz, 10 mW at 100 GHz, and 4 mW at 110 GHz. These results are comparable with those obtained from devices using gallium arsenide grown by other techniques such as vapor- or liquid-phase epitaxy.