802.11a、802.11a／g RF收发器

Maxim推出两款用于单频802.11a和双频802.11a/g WLAN设备的单片RF收发器。其中MAX2828工作在4.9GHz-5.9GHz的频段，MAX2829工作在2.4GHz-2.5GHz和4.9GHz-5.9GHz两个频段，这两款器件都具有MIMO（多入多出）模式，在发射/接收期间其本地振荡器的相位角恒定不变，能够使多个收发器与系统参考时钟同步。MAX2828/MAX2829收发器采用Maxim公司专有的高性能SiGe BiCMOS制造工艺，     

Design of a Silicon Beam Resonator for a Novel Gas Sensor

研究了一种基于硅悬臂梁谐振器的新型气体传感器.该传感器在敏感环境中,可同时获得敏感膜电导率和质量变化,测量被测气体分子的荷质比,具有高灵敏度和高选择性.根据这一原理,针对气体传感器的需求,设计了硅悬臂梁谐振器化学传感器结构,进行了仿真优化,并采用MEMS表面牺牲层工艺制备该器件,激光频率仪测量验证了该微型谐振梁的谐振频率.     

fMRI-BCI： a Review

Functional magnetic resonance imaging （fMRI） is a new tool for brain-computer interface （BCI）. This paper presents an overview to fMRI-BCI. Our attention is mainly put on the methods of signal acquisition, signal preprocessing, and signal analysis of basic fMRI-BCI structure. The available softwares and the applications of fMRI-BCI are briefly introduced. At last, we suggest focusing on some technologies to make fMRI-BCI more perfect.     

Supercontinuum generation in a Bragg fiber：a novel proposal

Nonlinear optical effects such as self-phase modula-tion,four-wave mixing,cross-phase modulation,sti mula-ted Raman scattering,together with appropriate tempo-ral dispersion profileinan optical fiber couldsignificant-ly broaden ( >100 nm) the spectrumof a…     

The blue laser race — a marathon not a sprint

Throughout the past year III–Vs Review has been reporting on the starting developments within the field of blue emitting optoelectronics. Previous years saw a re-awakening of the science and commercial pursuit of what had been dismissed as a cul de sac in compound semiconductors. 1997 saw confirmation of the blue-green laser diode as an operational device from researchers worldwide, both in the academic laboratories and in industry. As the year closes and we look forward to the ‘wash-up’ celebration at the ‘MRS Fall Meeting Nitride Workshop’, Roy Szweda reports on the very latest developments in this exciting field.     

An antenna system using a plasma column having a central conductor and excited by a co-axial line†

The radiation pattern of an open-ended co-axial line excited in the TEM mode in a plasma column having a central conductor along the axis is studied. The field distribution at the open-end cross-section of the co-axial line is assumed to be equivalent to the vector sum of magnetic current rings of various radii, ranging from the outer radius of the inner conductor to the inner radius of the outer conductor of the co-axial line at the open end. The radiation field is obtained as a vector sum of field components duo to individual rings of magnetic current. This type of configuration gives rise to a veil-enhanced radiation peak near and before the critical angle. The amplitude of the radiation peak depends upon the dimensions of the plasma column, the diameter of the central conductor and the inner diameter of the outer conductor of the coaxial line at the open end. Its direction can be changed by changing the plasma density. Based upon these results it is proposed to develop an electronically scannable narrow-beam plasma antenna system.     

Everyone has a reason

在这个科技产品日新月异的年代，却有像诺基亚1100这样的无名小卒，自2003年开卖以来，已经卖出了超过两亿台。是的，这款便宜耐用的机器销售量已经远超过了 ipod 家族（一亿台）、RAZR 家族（五千万台）、甚至是PS2家族（一亿一千五百万台）。     

先科M1a

功能丰富的音/视频播放手机。M1a是先科强力推出的M系列影音手机中的第一款产品。该机支持MP4影音文件下载/播放,可播放超长视频文件,电影、MTV,内置MP3播放器且随机配送优质立体声耳机,26 万色的2.0寸超大TFT内屏,全屏播放配合高保真动感音效,效果非同凡响,可给用户提供视觉,听觉的双重愉悦感受。     

不只是a little more

iRqone5的热潮还未散尽,但苹果似乎认为市场反应还不够激烈。10月23日,蹈Phone5发布会仅一个月的时间,苹果发布会再次降临。坦言讲,Padmn和iPhone5堪称一对“难兄难弟”,谁都没有逃脱被剧透的厄运,从接口到尺寸、从零件图到样机实物,相信即使没有这场发布会大家也都清楚地知道关于iPadmini的一切信息。再加上23日是周二,第二天大家都要照常上班,我对当天晚匕熬夜直播苹果Padmini发布会,是否有人收听并不报太大希望,所以打开直播问看到800多人在线翘首等待着实让我吃惊不已。     

Design of a dual-channel multi-mode GNSS receiver with a∑△fractional-N synthesizer

A 72 mW highly integrated dual-channel multimode GNSS(global navigation satellite system) receiver with aΣ△fractional-N synthesizer which covers GPS L1 and the Compass B1/B2/B3 band is presented.This chip was fabricated in a TSMC CMOS 0.18μm process and packaged in a 48-pin 3×3 mm~2 land grid array chip scale package.This work achieves NF≤5.3 dB without an external LNA,channel gain = 105 dB for channel one (Compass B2 and B3 band),and channel gain = 110 dB for channel two(GPS L1 and Compass B1 band).Image rejection(IMRR) = 36 dB,phase noise is -115.9 dBc @ 1 MHz and -108.9 dBc @ 1 MHz offset from the carrier for the two channels separately.At the low power consumption,multibands of GNSS are compatible in one chip, which is easy for consumers to use,when two different navigation signals are received simultaneously.     

Performance of a Self-Aligned InP/GaInAs SHBT with a Novel T-Shaped Emitter

研究了一种采用新的T型发射极技术的自对准InP/GaInAs单异质结双极晶体管.采用了U型发射极图形结构、选择性湿法腐蚀、LEU以及空气桥等技术,成功制作了U型发射极尺寸为2μm×12μm的器件.该器件的共射直流增益达到170,残余电压约为0.2V,膝点电压仅为0.5V,而击穿电压超过了2V.器件的截止频率达到85GHz,最大振荡频率为72GHz,这些特性使此类器件更适合于低压、低功耗及高频方面的应用.     

A DC-Offset Cancellation Scheme in a Direct-Conversion Receiver for IEEE 802.11a WLAN

提出了一种符合IEEE802.11a无线局域网的5GHz直下变频接收机解决直流漂移的方法. 该方法利用双平衡混频器输出端的模拟反馈环路消除直流漂移. 该混频器经过测试，在5.15GHz频率下具有9.5dB的转换增益，13.5dB的噪声系数和7.6dBm的三阶交调，在3.3V电源电压条件下67mW的功耗，以及1.73mV的直流漂移，并能使直流漂移减少76%. 该方案及整个直下变频的WLAN接收机已经采用0.35μm SiGe BiCMOS工艺流片并测试.     

Probabilistic teleportation of a two-particle entangled state via a partially entangled pair

1 Introduction In the burgeoning field of quantum information theory, people have found many remarkable applications of quantum mechanics [1?4]. One of the striking nontrivial techniques in quantum information is the existence of the procedure called quan…     

A DBRTD with a High PVCR and a Peak Current Density at Room Temperature

AlAs/GaAs/In0.1Ga0.9As/GaAs/AlAs double-barrier resonant tunneling diodes(DBRTDs) grown on a semi-insulated GaAs substrate with molecular beam epitaxy is demonstrated.By sandwiching the In0.1Ga0.9As layer between GaAs layers,potential wells beside the two sides of barrier are deepened,resulting in an increase of the peak-to-valley current ratio (PVCR) and a peak current density.A special shape of collector is designed in order to reduce contact resistance and non-uniformity of the current;as a result the total current density in the device is increased.The use of thin barriers is also helpful for the improvement of the PVCR and the peak current density in DBRTDs.The devices exhibit a maximum PVCR of 13.98 and a peak current density of 89kA/cm2 at room temperature.     

银妆 HP Pavilion a1070cl

最新的HP畅游人系列家用PC来了，这一次它那保守的“黑色外衣”不见了，取而代之的是时尚亮丽的“银色新装”。同时HP官方表示，今后几年的时间内，HP家用系列产品将会一直沿用这一银色主题，今后HP银将有望成为继IBM黑、苹果白之后的第三种lT厂商的招牌色调。在HP最新的畅游人系列家用PC中，最吸引人的莫过于本文的主角HP a1070cl了，它是HP本次发布的新机中惟一一款偏重游戏功能的PC。     

A susceptor with a ∧-shaped slot in a vertical MOCVD reactor by induction heating

By using the numerical simulation for the temperature field in the metal organic vapor deposition （MOCVD） reactor by induction heating, it is found that the temperature distribution in the conventional cylinder-shaped susceptor is nonuniform due to the skin effect of the induced current, which makes the temperature distribution of the wafer nonuniform. Therefore, a novel susceptor with a A-shaped slot is proposed. This slot changes the mode and the rate of the heat transfer in the susceptor, which improves the uniformity of the temperature distribution in the wafer. By using the finite element method （FEM）, the susceptor with this structure for heating a wafer of four inches in diameter is optimized. It is observed that the optimized susceptor with the A-shaped slot makes the uniformity of the temperature distribution in the wafer improve by more than 85%, and a good uniformity of temperature distributions is kept under different wafer temperatures, which may be beneficial to the film growth.     

随性枉士——索尼a350

在2008年以前,索尼一年一款产品地推出了a100和a700,尽管颇有新意,在一段时间内也造成了较大影响,但整个DSLR市场格局却依旧是老样子。人们甚至觉得：索尼还有待成熟。不过,进入2008年,一切都开始改变,索尼终于暴露出它的“杀手”本色,连续发布三款入门级产品,不但形成了自己在这块市场的完美布局,更从价格、拍摄便利性方面给对手以致命打击,在市场上掀起一阵阵热潮。如果要用什么来比喻,那么它应该是DSLR中的米芾书法：得“二王”精髓,结体欹侧多姿,用笔“八面出锋”,变化多端,才情毕露——以a350为首的索尼入门级DSLR产品线正是这种风格的典型代表。     

低端实用翻盖机 诺基亚3610a

诺基亚的大多数翻盖手机都面向低端市场,因此整体设计风格都非常相似。近日,一款型号为3610a的诺基亚最新翻盖手机正式发布了。看到这款3610a应该会让大家联想到另一款低端产品诺基亚3555,不过在功能配置上这款手机要明显强于诺基亚3555。