基于FPGA的紫外通信微弱信号放大器设计

摘要

According to the characteristics of the weak UV communication signals in free space near surface layer,the specific weak signal amplifier is designed.Based on the specifications of amplifiers,the composition and working princi-ple of the amplifier are analyzed.Integrated operational amplifier LMH6624MF and voltage control amplifier VCA61 0P are adopted to design preamplifier and post-amplifier respectively.AD921 4 is adopted to be as AD converter,and FPGA XC6VCX240T-2FF784 is adopted to design the frequency selective digital filter.The design and simulation are carried out by Multisim,Matlab and ISE.The results show that:the amplifier has continuously adjustable gain magnification be-tween 1 ~1 0000 at the center frequency of 30 kHz and 50 kHz,and the bandwidth near center frequency is about 4 kHz, the equivalent input noise voltage is ≤5 nV/ Hz@30 kHz,50 kHz,which satisfies specifications of the amplifier.The design using FPGA to filter has advantages of high accuracy,real-time,easy to upgrade.%针对近地层自由空间紫外通信信号微弱的特点，设计具体的微弱信号放大器。在提出放大器指标基础上，分析了放大器的组成与工作原理。运用LMH6624MF型号的集成运算放大器和VCA610P型号的电压控制放大器分别设计了前置放大器和后级放大器，采用AD9214作为AD转换，选用XC6VCX240T-2FF784型号的FPGA设计了选频数字滤波器。用Multi-sim、Matlab、ISE进行设计仿真验证，结果表明：该放大器在30 kHz 和50 kHz 两个中心频率具有1～10000之间连续可调的放大倍数，中心频率附近带宽约为4 kHz，等效输入噪声电压≤5 nV/ Hz ＠30 kHz，50 kHz，符合设计技术要求。设计中采用FPGA 实现滤波，具有精度高、实时性好、便于升级等优点。