基于MAX7042的低功耗FSK超外差接收电路设计

采用MAX7042设计了一种308MHz／315MHz／418MHz／433．92MHz低功耗FSK超外差式接收电路，该电路内置CMOS型超外差式射频（RF）接收芯片，具有高集成度、低功耗等特点，灵敏度为-110～-109dBm，接收频移键控（FSK）数据速率可达66kbps（NRZ）或33kbps（曼彻斯特），文中给出了MAX7042主要技术性能、内部结构、工作原理和应用电路。     

433/868/915MHz FSK/ASK/OOK无线收发器RF2945

RF2945是RFMicroDevices公司生产的一种单片射频收发芯片,利用该芯片可在433/868/915MHzISM频段进行FSK/ASK/OOK调制和解调。由于RF2945射频收发芯片内含射频发射、射频接收、PLL合成和FSK调制/解调等电路,因而可用于接收和发送数字信号。文中介绍了RF2945的结构原理和主要特性 ,同时给出了RF2945收发器的典型应用电路和使用注意事项     

可编程RF收发器芯片CC1000的原理及应用

CC1000是Chipcon公司新推出的单片可编程RF收发芯片，该芯片集成了射频发射，射频接收，PLL合成，FSK调制／解调，可编程控制等多种功能，其频率范围为300MHz-1000MHz,灵敏度为－109dBm,可编程输出功率为－20－10dBm，数据速率可达19.2kBaud。文中给出了CC1000的结构，原理，特性及应用电路。     

基于MAX7033的315MHz/433 MHz ASK超外差式接收电路设计

所设计的315 MHz/433 MHz ASK超外差式接收机电路采用MAX7033高集成度、低功耗CMOS、超外差式幅移键控(ASK)接收机,接收频率范围为300MHz～450 MHz,射频信号输入范围为-114 dBm～0 dBm,数据速率可达33 kb/s曼彻斯特码率(66 kb/s NRZ).介绍了MAX7033的主要技术性能、内部结构、工作原理和应用电路.     

飞利浦为无线射频收发器整合进下一代双模四波段手机设定标准

皇家飞利浦电子集团推出了新型单片无线射频收发器 ,该产品用于支持四波段、GSM/ GPRS和全EDGE发射 /接收操作的 2 G和 2 .5 G手机。 UAA35 37RF收发器代表了市场上最先进的解决方案之一 ,为将 RF整合进手持设备设定了新标准 ,用户可在全球部署了基于 GSM的 2 G和 2 .5 G蜂窝网络的地点使用这些手持设备。接收器信道内四个集成的可编程低噪音放大器(L NA)使亚洲的设计人员可以设计在 85 0 MHz,90 0 MHz,180 0 MHz和 190 0 MHz四个波段 ,或在其中两个或三个波段范围内使用的手机。对于亚洲的手持设备生产商来说 ,新的 RF收发…     

基于超低功耗无线芯片SX1212的无线数传模块设计

SX1212是SEMTECH公司推出的一款超低功耗的单芯片无线芯片,频率范围从300MHz到510MHz.SX1212经过优化具有非常低的接收功耗,典型接收电流为2.6mA,远小于同类收发器的接收电流.工作电压为2.1V～3.6V,最大发射功率+12.5dBm,SX1212集成度非常高,其包含了射频功能和逻辑控制功能的集成电路,内部集成压控振荡器、锁相环电路、功率放大电路、低噪声放大电路、调制解调电路、变频器中放电路等.此外它整合了基带调制解调器的数据传输速率高达150Kbps数据处理功能包括一个64字节的FIFO,包处理,自动CRC生成和数据白化.它的高度集成的架构允许最少的外部元件数量,同时保持设计的灵活性.所有主要的射频通讯参数可编程,其中多数可动态设置.它符合欧洲(ETSI EN 300-220 V2.1.1)和北美(FCC part 15.247 and 15.249)标准.     

单片AMPS／TDMA射频解决方案

传统上．蜂窝AMPS手机的接收和发送功能是采用两片或更多片芯片实现的，主要是为了保证敏感的射频（RF)前端接收电路与发送路径中的大功率干扰信号相隔离。设计人员所面临的挑战在于既要尽可能降低总体系统解决方案成本，同时又要保证性能。尽可能减少器件的数量和提高功能的集成度，并可以在不影响功能的情况下降低总成本以及手机射频部分的体积。     

三星SGH-NXXX系列手机 完全无接收信号检修

三星SGH-NXXX系列手机没有信号条,是接收电路故障。接收电路故障可以按天线符号出来的快慢进行判断。1.开机后天线符号立即出来,但无信号条,一般为射频电路某个环节出现故障。为了确诊是否为射频电路故障,可用示波器测接收I/Q,应看不到I/Q基带信号。检修方法:将频谱分析仪的中心频率开到225MHz,带宽调到0.2MHz,不接任何衰减按钮,测第     

RF收发器芯片支持双模式四频段移动电话机

Philips Electronics公司业已推出一种适用于第二代和第2.5代移动电话机的单芯片射频(RF)收发器。这种用全硅BiCMOS工艺制造的UAA3537型RF收发器,具有一个公共RF内核,用以支持4频段的GSM/GPRS和全EDGE收/发操作方式。 UAA3537收发器的工作电压为2.4～3.0V。它在接收信道使用4个可编程低噪声集成放大器,从而允许设计师配置可在850MHz、900MHz、1800MHz和1900MHz四个频段工作的     

超低接收电流的MRF89XA收发器

Microchip TechnologyInc．（美国微芯科技公司）推出3mA超低接收电流的新型MRF89XA收发器,可延长868、915和950MHz Sub—GHz无线网络中电池的使用寿命。868MHzMRF89XAM8A和915MHz MRF89XAM9A收发模块可消除设计射频（RF）电路的复杂性和获得机构认证的成本,加速设计周期。     

Performance improvement in tensile-strained In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As metamorphic HEMT

This paper proposes a In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As (x=0.3-0.5-0.3) metamorphic high-electron mobility transistor with tensile-strained channel. The tensile-strained channel structure exhibits significant improvements in dc and RF characteristics, including extrinsic transconductance, current driving capability, thermal stability, unity-gain cutoff frequency, maximum oscillation frequency, output power, power gain, and power added efficiency.     

Very low-noise Al/sub 0.3/Ga/sub 0.7/As/Ga/sub 0.65/In/sub 0.35/As/GaAs single quantum-well pseudomorphic HEMTs

AlGaAs/GaInAs/GaAs pseudomorphic HEMTs with an InAs mole fraction as high as 35% in the channel has been successfully fabricated. The device exhibits a maximum extrinsic transconductance of 700 mS/mm. At 18 GHz, a minimum noise figure of 0.55 dB with 15.0 dB associated gain was measured. At 60 GHz, a minimum noise figure as low as 1.6 dB with 7.6 dB associated gain was also obtained. This is the best noise performance yet reported for GaAs-based HEMTs.<>     

A 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode array

We report a 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode (APD) array. The mean breakdown voltage of the APD was 57.9 V and the standard deviation was less than 0.1 V. The mean dark current was /spl sim/2 and /spl sim/300 nA, and the standard deviation was /spl sim/0.19 and /spl sim/60 nA at unity gain (V/sub bias/ = 13.5 V) and at 90% of the breakdown voltage, respectively. External quantum efficiency was above 40% in the wavelength range from 1.0 to 1.6 /spl mu/m. It was /spl sim/57% and /spl sim/45% at 1.3 and 1.55 /spl mu/m, respectively. A bandwidth of 13 GHz was achieved at low gain.     

Al/sub 0.3/Ga/sub 0.7/As/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) doped-channel field-effect transistors (DCFET's)

The properties of both lattice-matched and strained doped-channel field-effect transistors (DCFET's) have been investigated in AlGaAs/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) heterostructures with various indium mole fractions. Through electrical characterization of grown layers in conjunction with the dc and microwave device characteristics, we observed that the introduction of a 150-/spl Aring/ thick strained In/sub 0.15/Ga/sub 0.85/As channel can enhance device performance, compared to the lattice-matched one. However, a degradation of device performance was observed for larger indium mole fractions, up to x=0.25, which is associated with strain relaxation in this highly strained channel. DCFET's also preserved a more reliable performance after biased-stress testings.<>     

Morphological and electrical characterization of SixCryCzBv thin films

Si_xCr_yC_zB_v thin films with several compositions have been studied for integration of high precision resistors in 0.8 μm BICMOS technology. These resistors, integrated in the back-end of line, have the advantage to provide high level of integration and attractive electrical behavior in temperature, for analog devices. The film morphology and the structure have been investigated through transmission electron microscopy analysis and have been then related to the electrical properties on the base of the percolation theory. According to this theory, and in agreement with experimental results, negative thermal coefficient of resistance (TCR) has been obtained for samples with low Cr content, corresponding to a crystalline volume fraction below the percolation threshold.Samples with higher Cr content exhibit, instead, a variation of the TCR as a function of film thickness: negative TCR values are obtained for thickness lower than 5 nm, corresponding to a crystalline volume fraction below the percolation threshold; positive TCR are obtained for larger thickness, indicating the establishment of a continuous conductive path between the Cr rich grains. This property seems to be determinant in order to assure the possibility to obtain thin film resistors almost independent on the temperature.     

Highly linear Al/sub 0.3/Ga/sub 0.7/N-Al/sub 0.05/Ga/sub 0.95/N-GaN composite-channel HEMTs

We report an Al/sub 0.3/Ga/sub 0.7/N-Al/sub 0.05/Ga/sub 0.95/N-GaN composite-channel HEMT with enhanced linearity. By engineering the channel region, i.e., inserting a 6-nm-thick AlGaN layer with 5% Al composition in the channel region, a composite-channel HEMT was demonstrated. Transconductance and cutoff frequencies of a 1 /spl times/100 /spl mu/m HEMT are kept near their peak values throughout the low- and high-current operating levels, a desirable feature for linear power amplifiers. The composite-channel HEMT exhibits a peak transconductance of 150 mS/mm, a peak current gain cutoff frequency (f/sub T/) of 12 GHz and a peak power gain cutoff frequency (f/sub max/) of 30 GHz. For devices grown on sapphire substrate, maximum power density of 3.38 W/mm, power-added efficiency of 45% are obtained at 2 GHz. The output third-order intercept point (OIP3) is 33.2 dBm from two-tone measurement at 2 GHz.     

Comparison between Pt/TiO2/Pt and Pt/TaOX/TaOY/Pt based bipolar resistive switching devices

Nonvolatile memories have emerged in recent years and have become a leading candidate towards replacing dynamic and static random-access memory devices. In this article, the performances of TiO₂ and TaO₂ nonvolatile memristive devices were compared and the factors that make TaO₂ memristive devices better than TiO₂ memristive devices were studied. TaO₂ memristive devices have shown better endurance performances (10⁸ times more switching cycles) and faster switching speed (5 times) than TiO₂ memristive devices. Electroforming of TaO₂ memristive devices requires~4.5 times less energy than TiO₂ memristive devices of a similar size. The retention period of TaO₂ memristive devices is expected to exceed 10 years with sufficient experimental evidence. In addition to comparing device performances, this article also explains the differences in physical device structure, switching mechanism, and resistance switching performances of TiO₂ and TaO₂ memristive devices. This article summarizes the reasons that give TaO₂ memristive devices the advantage over TiO₂ memristive devices, in terms of electroformation, switching speed, and endurance.     

Electrooptic ferroelectric Na/sub 0.5/K/sub 0.5/NbO/sub 3/ films

We report on waveguiding and electrooptic properties of epitaxial Na/sub 0.5/K/sub 0.5/NbO/sub 3/ films grown by radio-frequency magnetron sputtering on Al/sub 2/O/sub 3/(11_02) single crystal substrates. High optical waveguiding performance has been demonstrated in infrared and visible light. The in-plane electrooptic effect has been recorded in transmission using a transverse geometry. At dc fields, the effective linear electrooptic coefficient was determined to 28 pm/V, which is promising for modulator applications.