光纤多路模拟电视传输

本文指出光纤通信除在公用和专用数字通信网发挥广泛作用外,近年又在模拟电视传输和有线电视网开展新兴业务,利用多路宽带传输代替原先的单路基带传输。在副载波频分多路的频段内,每路有调频和调幅两种方式。沿干线传输电视,每路宜用调频,而在有线电视分配网,每路宜用残留边带调幅。单模光纤的工作波长倾向于使用1.3μm,而不是1.55μm。为此,1.3μmDFB激光管是关键器件,应具有高线性特性,以便同时传输较多路数的电视,又要求提供大功率,以便扩大服务用户数。光纤多路电视非常需要光放大器,半导体行波放大管对每路调频是适宜的,对每路调幅则限制频级的最高与最低频率比不大于2。氧化物光纤掺镨可望制成1.3μm光纤放大器。     

Improving the Performance of Sampled-Grating DBR Laser-Based Analog Optical Transmitters

In this paper, the available analog link performance of integrated transmitters containing a sampled-grating distributed Bragg reflector laser, a semiconductor optical amplifier, and a modulator is evaluated. It is found that to provide a link gain and a low-noise figure, an RF preamplifier is required, and for this reason, spurious-free dynamic range (SFDR) including a preamplifier has been evaluated. An SFDR of 110-dBHz^2/3, a noise figure of 5.4 dB, and link gain of 6.9 dB at 5 GHz is obtained. It is further investigated how link SFDR can be improved by linearization techniques. Two novel approaches are proposed and demonstrated: first, predistortion by extraction of nonlinear components from an integrated second modulator exposed to the same wavelength, optical power and temperature for matched nonlinear terms; second, a novel linearized modulator configuration balancing electroabsorption and Mach-Zehnder modulation that can reach a null for both second- and third-order intermodulation products at a single bias point.     

Linearization of Phase-Modulated Analog Optical Links Employing Interferometric Demodulation

We present a linearized phase-modulated analog photonic link that utilizes parallel interferometric demodulation to suppress the third-order intermodulation distortion present in the link. By utilizing two parallel interferometers with different differential delays, we are able to balance the third-order distortion in the output photocurrent and achieve a fifth-order limited link response. We demonstrate shot noise-limited spurious-free dynamic ranges of ~ 130 dB (1-Hz bandwidth) at ~ 1 GHz for a total DC photocurrent I_dc~ 8 mA and ~ 131 dB (1-Hz bandwidth) at ~ 5 GHz for a total DC photocurrent I_dc ~ 7 mA . These results represent a nearly two order-of-magnitude improvement in dynamic range over conventional intensity- or phase-modulated analog photonic links for a fixed received photocurrent.     

Optimizing Optical Transmitters and Receivers for Transmitting Multichannel Video Signals Using Laser Diodes

Analog transmission using laser diodes is quite attractive for transmitting multiplexed video signals, owing to the wide modulation bandwidth of laser diodes. Optimizations for transmitting color-TV signals (7 channel frequency division multiplexed) in the VHF band using buried heterostructure laser diodes are investigated. The major transmission objectives are a carrier to noise ratio of larger than 48 dB and intermodulation products of less than -55 dB. Design curves for minimizing distortion at the transmitter are demonstrated. A modulation index of 70 percent is shown to be capable of attaining the objective. Both the avalanche photodiode (APD) and the pinphotodiode (PD) are considered for use in the receiving amplifier. Minimum receiving power of -11 dBm obtained with the PD receiver is in good agreement with theoretical values. Deterioration of signal to noise ratio due to fiber guided transmissions is also reviewed in comparison with aerial transmissions.     

微波回传系统发射机数字预失真线性化

微波回传系统是宽带无线通信基站信号回传的主要手段之一.对19GHz微波回传系统发射机的非线性特性进行了实验测试与分析研究,采用基于查找表(LUT)的数字预失真技术对其进行线性化以满足大容量无线基站信号传输的需求.利用指数加权移动平均算法(EWMA)提取发射机的静态非线性特性以构建数字预失真查找表.使用3载波WCDMA信号进行实验验证,实验结果表明采用查找表数字预失真器对该被测发射机进行线性化,3阶互调失真(IMD3)最大可以改善23dB.因此通过简单的查找表数字预失真技术可以有效地提高微波回传系统发射机的线性度,同时可以使微波功率放大器工作在较高的输出功率,增大回传距离,降低生产成本.     

外调制CATV光发射机前馈补偿的理论分析

本文在对外调制光AM CATV发射机原理及其非线性补偿技术进行阐述的基础上,重点论述了BBI调制器的前馈补偿方案的原理和系统结构,并对这一方案的关键技术进行了详细的理论分析.     

Neural-Network-Based Robust Linearization and Compensation Technique for Sensors Under Nonlinear Environmental Influences

A novel artificial neural network (NN)-based technique is proposed for enabling smart sensors to operate in harsh environments. The NN-based sensor model automatically linearizes and compensates for the adverse effects arising due to nonlinear response characteristics and nonlinear dependency of the sensor characteristics on the environmental variables. To show the potential of the proposed NN-based technique, we have provided results of a smart capacitive pressure sensor (CPS) operating under a wide range of temperature variation. A multilayer perceptron is utilized to transfer the nonlinear CPS characteristics at any operating temperature to a linearized response characteristics. Through extensive simulated experiments, we have shown that the NN-based CPS model can provide pressure readout with a maximum full-scale error of only 1.5% over a temperature range of 50 to 200 with excellent linearized response for all the three forms of nonlinear dependencies considered. Performance of the proposed technique is compared with a recently proposed computationally efficient NN-based extreme learning machine. The proposed multilayer perceptron based model is tested by using experimentally measured real sensor data, and found to have satisfactory performance.     

1550nm光传输系统中的外调制光发射机

本在对1550nm光传输系统性能在分析的基础上，详细阐述了1550nm外调制光发射机设计的原理、方法和注意事项。     

Improved Large Signal Analysis of the Dual-Wavelength Linearization Technique of Optically Phase-Modulated Analog Microwave Signals

This paper presents simple closed-form expressions, in terms of the ordinary Bessel functions, for the amplitudes of the third- and fifth-order intermodulation products of the dual-wavelength linearized phase modulated link for any scenario of the microwave driving voltage. The results obtained for a microwave driving voltage comprising equal-amplitude two- and three-tones show that the third-order intermodulation can be minimized for values of phase modulation depth less than 0.2 over a relatively wide range of the ratio between the powers in the TM and TE waves of the link. Using these results it is possible to adjust the phase modulation depth and/or the ratio between the powers of the TM and TE waves to achieve a dual-wavelength linearized phase modulated link with a predetermined intermodulation performance.     

Analog/RF Performance of Multichannel SOI MOSFET

In this paper, for the first time, we present a detailed RF experimental and simulation study of a 3-D multichannel SOI MOSFET (MCFET). Being different from the conventional planar technology, the MCFET features a total of three self-aligned TiN/HfO₂ gate stacks fabricated on top of each other, allowing current to flow through the three undoped ultrathinned silicon bodies (UTBs). In other words, the operation of the MCFET is theoretically based on two UTB double-gate SOIs and a single-gate UTB fully depleted SOI (FDSOI) at the bottom. Using on-wafer S-parameters, the RF/analog figures-of-merit of an MCFET with a gate length of 50 nm are extracted and discussed. Thanks to the enormous transconductance (gm) and very low output conductance, the RF/analog performances of MCFET-voltage gain (A _VI) and early voltage (V _EA) are superior compared with that of the single-gate UTB-FDSOI. However, these advantages diminish in terms of transition frequency (fT), due to the large total input gate capacitances (C _GG). This inspires the introduction of spacer engineering in MCFET, aiming at improving both C _GG and fT. The sensitivity of the spacer length to the RF/analog performances is experimentally analyzed, and the performance optimization is validated using ac simulation. This paper concludes that optimized MCFETs are a serious contender to the mainstream MOSFETs including FinFETs for realizing future low-power analog applications.     

一种模拟预失真线性化微波功率放大器

研究了一种新的模拟预失真线性化电路,它由2对工作于不同偏置电压下的反向并联肖特基二极管对以及电容、电阻,3 dB电桥耦合器(Hybrid)、可变增益放大器组成,通过调节二极管对的偏置电压可分别控制产生IM3和IM5信号的幅度和相位。利用专用的微波电路仿真工具ADS进行仿真验证,仿真结果表明在2 GHz频段功率放大器的增益压缩和相位偏移在1 dB压缩点附近分别补偿了1.5 dB和9.3°,双音测试表明,在输出功率为41.8 dBm时,IMD3和IMD5分别改善了26和10 dB。     

2.5Gb/s混合集成光发射机

介绍了适用于光纤通信系统且具有完全自主知识产权的混合集成光发射机的研制.该发射机采用薄膜电路和激光焊接耦合技术将高速集成电路和光电子器件进行混合集成,其中高速集成电路是采用0.35μm硅CMOS工艺实现的单片4∶1复接器加激光驱动器芯片,光电子器件是采用湿法腐蚀、聚合物平坦和lift-off等技术实现的激光器芯片,最终混合集成模块采用蝶形管壳进行封装,体积小、性能优良.该发射机工作速率为2.5Gb/s,波长为1550nm,输出光功率为5.5dBm,消光比为9.4dB.     

2.5Gb/s混合集成光发射机

介绍了适用于光纤通信系统且具有完全自主知识产权的混合集成光发射机的研制.该发射机采用薄膜电路和激光焊接耦合技术将高速集成电路和光电子器件进行混合集成,其中高速集成电路是采用0.35μm硅CMOS工艺实现的单片4∶1复接器加激光驱动器芯片,光电子器件是采用湿法腐蚀、聚合物平坦和lift-off等技术实现的激光器芯片,最终混合集成模块采用蝶形管壳进行封装,体积小、性能优良.该发射机工作速率为2.5Gb/s,波长为1550nm,输出光功率为5.5dBm,消光比为9.4dB.     

多通道模拟监视器件AMC7820的原理及应用

AMC7820是德州仪器公司(TI)推出的专为多通道应用而设计的模拟监视与控制电路。它内含一个8通道12位模数转换器、3个12位数模转换器、9个运算放大器、1个热控电流源、1个内部 2.5V基准和1个SPI串行接口。应用该器件可对光放大器中的泵激光电流和热电致冷器(TEC)以及DWDM(利用光波长进行数据传输)应用中的光功率进行控制和监控，并可大大降低成本。文中介绍了AMC7820的基本原理、管脚功能和应用电路。     

Expected Crosstalk Performance of Analog Multichannel Subscriber Carrier Systems

This paper determines the intelligible crosstalk performance of analog multichannel subscriber carrier systems. Using a 0.1 percent probability of intelligible crosstalk objective, the calculations determine that the equal level far-end crosstalk loss must exceed 55.6 dB. Based on crosstalk measurements of in-service cables in South Central Bell, it is shown that only a small fraction of the pairs fail the crosstalk objective. Hence, it is concluded that multichannel analog subscriber carrier systems can be applied without any cable crosstalk constraints.     

高速传输系统的偏振模色散补偿技术

随着光网络的快速发展,系统的传输码率逐渐提升,传输技术也不断地发展和完善。光纤传输系统中的各种因素造成的影响程度也出现了很大的变化。针对偏振模色散(PMD)对高速光纤传输系统造成的损害,对目前光域和电域的PMD补偿技术进行详细的阐述。通过比较各种方案,指出高速光纤传输系统中PMD的光域补偿技术更适用,发展空间大,而且性能好。其中光纤光栅补偿技术应用广泛,对单信道和多信道传输系统都适用。因此,光纤光栅技术最具发展潜力。     

光学多道分析仪系统光响应测量

实验测量和研究了光学多道分析仪系统的光谱响应、光强响应线性范围和道的光强响应的均匀性问题，并讨论了实验结果。     

光学多道分析仪的波长定标

本文给出了与单光栅多色仪联用的光学多道分析仪的道数N与波长λ之间的对应关系,并用它对实验测得He-Ne灯与Bi-Ne空心阴极灯的光谱进行了定标,计算结果与标准值符合得很好。     

细胞显微荧光探测

本文报道在细胞生物学上利用光学多道分析仪取代传统的光电探测手段进行细胞荧光的探测以得到有关细胞组成、结构、功能和通讯等方面的信息的工作。一、利用光学多道分析仪测量细胞荧光的优点