激光小信号宽带放大器设计与实现

发布时间：2018-01-12 06:04

本文关键词：激光小信号宽带放大器设计与实现　出处：《华中师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：与其他测距技术相比,激光测距具有抗干扰能力强、测距精度高、测量距离远和能全天候工作等诸多优点,获得了广泛应用。近年来,以激光测距技术为基础的三维激光扫描仪,正在推动移动测量、三维实景地图等领域的快速发展,在国民经济和国防建设中具有非常重要的意义。作为三维激光扫描仪的核心部件之一的前端模拟电路,用于将激光小信号进行放大,其性能直接影响距离测量的精度和测距量程。前端模拟电路需要攻克以下几个关键技术难题：宽动态范围,模拟电路需具备较宽的动态范围,以适应不同距离、不同反射率目标的测距需求；大放大倍数,对于远距离和低反射率的反射物,需要大的放大倍数对微弱脉冲信号进行有效放大；宽带宽,三维激光扫描仪采用的激光器单个脉冲的脉宽在ns级,能量分布的带宽很宽；低噪声,降低噪声,提高信噪比,提高测距的精度。本文针对上述技术难题开展研究,首先分析了激光脉冲回波信号的特点,结合测距量程的要求,得出了本文激光小信号宽带放大器的设计技术指标；然后针对宽动态范围的激光测距要求,提出了多通道的设计方案；最后分模块详细阐述了激光小信号宽带放大器的设计。本文采用高响应速度和高灵敏度的铟镓砷APD作为前端光电探测器件,以跨阻放大器作为电路结构,设计了宽带宽、高灵敏度和低噪声的光电转换电路,放大倍数达69.5dB。为进一步减小噪声,采用过渡带特性最好的椭圆滤波器,完成了9阶120MHz带宽的椭圆滤波器设计；以高速电流反馈型差分运算放大器作为放大器主要器件,采用多级级联放大的方式,实现了28dB放大倍数的宽带放大器设计。经实验验证,本文设计的模拟电路方案简单实用、体积小,具有120MHz的系统带宽、97.5dB的总放大倍数和50mVpp总的系统噪声,能对各种反射率条件下不同目标物体反射回来的微弱激光小信号进行有效的放大。经测试,其最低激光检测灵敏度为1.1uW,有效测距量程大于300m,目前己成功应用于武汉海达数云技术有限公司首台自主研发的高精度三维激光扫描仪中。
[Abstract]:Compared with other ranging technology, laser ranging has strong anti-interference capability, high accuracy, long measurement distance and the advantages of all-weather work, has been applied widely. In recent years, 3D laser scanner using laser ranging technology as the foundation, is to promote the rapid development of mobile measurement, real three-dimensional map and other fields. Has a very important significance in the national economy and national defense construction. As the front one of the core parts of the 3-D laser scanner for analog circuit, amplify the laser small signal, its performance directly affects the precision of distance measurement and measurement range. The front-end circuit need overcome key technical problems as follows: wide dynamic range, analog circuit need to have a wide dynamic range, to meet the different needs of different target distances, ranging reflectivity; high magnification, with long distance and low reflectivity counter Shooting, need large amplification of weak pulse signal amplification; wide bandwidth, using 3D laser scanner laser single pulse width in the ns level, the energy distribution of wide bandwidth; low noise, reduce noise, improve SNR, improve the ranging accuracy. Aiming at the above problem research the paper analyses the characteristics of laser pulse echo signal, combined with the measurement range of requirements, the design of the technical index of laser small signal amplifier; and laser ranging in wide range dynamic requirements, puts forward the design scheme of multi channel; finally the module detailed design of broadband laser small signal amplifier. This paper uses the high the response speed and high sensitivity of InGaAs APD as front photoelectric detector, the transimpedance amplifier circuit is designed as structure, wide bandwidth, high sensitivity and low The noise of the photoelectric conversion circuit, amplification of 69.5dB. in order to reduce the noise further, using elliptic filter transition band. The best, completed the design of 9 order elliptic filter 120MHz bandwidth; with high speed current feedback type differential amplifier amplifier as the main devices, using multistage cascade way, realize the design of broadband amplifier 28dB amplification. After experimental verification, the design of analog circuit is simple and practical, small volume, the system bandwidth is 120MHz, the total magnification and 50mVpp total 97.5dB system noise, of weak laser small signal under the condition of various reflectance of different objects are reflected back effectively enlarged. After the test, the minimum laser detection the sensitivity is 1.1uW, the effective range is more than 300m, has been successfully applied in Wuhan Haida few clouds Technology Co. Ltd. the first independent research and development High precision three-dimensional laser scanner.

【学位授予单位】：华中师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN722

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