Amplified spontaneous emission spectrum and gain characteristic of a two-electrode semiconductor optical amplifier

A two-electrode multi-quantum-well semiconductor optical amplifier is designed and fabricated.The amplified spontaneous emission(ASE)spectrum and gain were measured and analyzed.It is shown that the ASE spectrum and gain characteristic are greatly influenced by the distribution of the injection current density.By changing the injection current density of two electrodes,the full width at half maximum,peak wavelength,peak power of the ASE spectrum and the gain characteristic can be easily controlled.     

A CMOS variable gain LNA for UWB receivers

A CMOS variable gain low noise amplifier(LNA) is presented for 4.2-4.8 GHz ultra-wideband application in accordance with Chinese standard.The design method for the wideband input matching is presented and the low noise performance of the LNA is illustrated.A three-bit digital programmable gain control circuit is exploited to achieve variable gain.The design was implemented in 0.13-μm RF CMOS process,and the die occupies an area of 0.9 mm~2 with ESD pads.Totally the circuit draws 18 mA DC current from 1.2 V DC supply,the LNA exhibits minimum noise figure of 2.3 dB,S(1,1) less than -9 dB and S(2,2) less than -10 dB.The maximum and the minimum power gains are 28.5 dB and 16 dB respectively.The tuning step of the gain is about 4 dB with four steps in all.Also the input 1 dB compression point is -10 dBm and input third order intercept point(IIP3) is -2 dBm.     

5V单电源供电的低噪声宽带放大器

以单片机MSP430F449为控制核心,设计了一个5 V单电源供电的低噪声宽带放大器。采用单位增益稳定低噪声运放OPA820作为前级放大,高速运放THS3091作为末级放大,其中利用DC-DC变换器TPS61087将5 V电压转化为18 V从而为末级放大电路供电。此外,系统还采用12位高速A/D转换器ADS803实现了测量并数字显示放大器输出电压峰峰值的功能,测量误差小于5%。本系统最高电压增益达到43 dB,上限及下限截止频率达到15 MHz和20 Hz,在50Ω负载上,最大不失真输出电压峰峰值为4.2 V。系统的输出噪声小于200 mV。     

数字电位器在加速度存储测试调理电路中的应用

针对跌落试验中双通道加速度存储测试仪,需要程控通道量程的需求,设计了基于贴片式非易失性数字电位器MAX5497,并结合C8051F340微处理器控制的增益可调节前置放大电路。文中较为详细地介绍了MAX5497芯片的主要特点、管脚功能和工作时序,给出了增益放大电路图,并利用微处理器对其反馈电阻进行程序设置。编写的相关电阻设置程序,对类似的增益放大电路设计有一定参考价值。     

宽带信号检测中自适应门限设定方法

在水声定位中,常常需要估计声波从发射端到接收端的传输时间。但由于传输距离的影响,接收到的声波信号强度变化范围很大,给检测带来不便。基于线性调频脉冲信号相关检测,提出了一种自适应门限设定方法,可以在一定的条件下替代自动增益控制电路。这一方法根据发射信号、传输信道、发射系统和接收系统的参数,依据声信号到达接收端的时刻,自动调整相关峰检测时的门限值,简便易行。仿真和湖上试验结果表明,这一方法可以有效地保证计算信号到达时刻的准确性。     

Wide‐Band Fine‐Resolution DCO with an Active Inductor and Three‐Step Coarse Tuning Loop

This paper presents a wide‐band fine‐resolution digitally controlled oscillator (DCO) with an active inductor using an automatic three‐step coarse and gain tuning loop. To control the frequency of the DCO, the transconductance of the active inductor is tuned digitally. To cover the wide tuning range, a three‐step coarse tuning scheme is used. In addition, the DCO gain needs to be calibrated digitally to compensate for gain variations. The DCO tuning range is 58% at 2.4 GHz, and the power consumption is 6.6 mW from a 1.2 V supply voltage. An effective frequency resolution is 0.14 kHz. The phase noise of the DCO output at 2.4 GHz is –120.67 dBc/Hz at 1 MHz offset.     

某型混联微光像增强器增益漂移问题研究

为解决某型混联微光像增强器在生产过程中出现高、低温增益超占比较高的问题,分析像增强器增益产 生温度漂移的原理,研究常温、低温和高温条件下的增益变化规律,并采用Minitab 软件分析像增强器的增益与温 度相关性,拟合出增益-温度回归函数,据此确定常温增益的调节范围。结果表明：该方法能降低该型微光像增强器 增益漂移超范围的风险,有效提高产品质量。     

槽区加载介质矩形格栅慢波结构的色散与增益

建立了槽区内加载介质的格栅慢波结构模型.通过Borgnis函数法和场匹配法得到冷态和热态色散方程.并推导了耦合阻抗的表达式.在稀疏电子注的假设下,求得增益近似解的表达式.通过数值方法,求解并分析了加载介质对色散关系、基波耦合阻抗、基波相速和基波增益的影响.并指出分别在槽内加载介质和格栅对侧加载介质对高频特性的不同影响趋势.     

用于毫米波段行波管的可调预失真器

提出了满足行波管功率放大器(TWTA)要求的毫米波段的可调预失真线性化器,该预失真器基于90°定向耦合器、GaAs肖特基二极管、微带线和负载电阻,产生预失真信号。通过调节GaAs肖特基二极管的偏置电压、微带线电长度及负载电阻可以得到不同的增益扩展和相位扩张效应,在频率为29 GHz~31 GHz和额定输入功率范围内,增益扩展范围为5 dB~11.5 dB,相位扩张范围为35°~65°。仿真及实测结果表明:该预失真电路可调性强,满足通信工程TWTA的补偿需求。     

基于共形馈电网络的新型双频四臂螺旋天线

针对卫星地面手持终端系统对天线高效率宽波瓣的应用要求,文章提出一种新型双频印刷一体化四臂螺旋天线结构,通过两种方式提高其双频辐射效率:第一,每组辐射振子分成两个支路,分别以不同的长度、宽度和螺旋角度绕制以减少振子间耦合,同时覆盖两个不同的频点;第二,馈电网络和辐射振子进行一体化设计,提高其馈电效率。测试结果表明:在两个间距很近的频点(1.1倍频程)能够分别实现4.3dBi(低频)和4.2dBi(高频)的右旋圆极化增益,且4dBi以上右旋圆极化增益相对频带宽度分别为6%(低频)和5%(高频),圆极化3dB波瓣宽度均达到130°以上。该天线的双频点、宽波束、高效率性能适合于卫星通信手持终端系统应用。