激光测距系统整形模块和低通滤波模块优化设计  

Optimization of shaping circuit and low-pass filter in laser ranging system

作　　者：尤政[1,2] 杨冉[1,2] 张高飞 薛旭峰[1] 叶良琛 

机构地区：[1]清华大学精密仪器系,北京100084 [2]清华大学精密测试技术及仪器国家重点实验室,北京100084

出　　处：《光学精密工程》2013年第10期2527-2534,共8页Optics and Precision Engineering

基　　金：国家863高技术研究发展计划资助项目(No.20124302056)

摘　　要：由于减小相位式激光测距系统的鉴相误差可提高测距精度,本文对鉴相器前置整形模块和后置滤波模块进行了优化设计,以提高鉴相精度。针对整形模块,引入了迟滞比较器,克服了传统开环比较电路在实际噪声条件下存在的多重触发缺陷,解决了鉴相器输出方波高电平宽度不稳定的问题。针对滤波模块,介绍了基于MC4044鉴相芯片的两种典型放大/滤波电路及其缺陷,使用FilterPro软件设计了4阶有源低通滤波器,并说明了它相对于典型设计的优势。实验结果表明:相比于开环比较器,本文设计的迟滞比较器避免了接地(GND)噪声引起的多重跳变现象,输出方波的上升沿时间由1.66μs下降为108ns;与基于MC4044的两种典型放大/滤波模块设计相比,本文设计的低通滤波电路克服了输出DC电平值非线性变化的缺陷线性度(R2)值由0.908 3提高至0.999 9)和灵敏度较低的缺陷(转化增益常量提高了96.5%),而输出DC电平上的干扰信号峰峰值则由50～230mV下降至10～20mV,有效减少了后级的A/D采样误差,提高了鉴相精度。As the phase discrimination error of a phase laser ranging system effects its ranging accuracy,this paper optimizes the designs of a preceding stage （shaping circuit） and a subsequent stage （low-pass filter） in the phase detector.For the shaping circuit,a eomparator with hysteresis was designed to avoid the multiple-triggered phenomenon caused by the noise on GND for open loop filters,and stabilizes the output of phase detector.For the low-pass filter,two typical amplifier/filter circuits based on MC4044 and their defects were introduced,a 4th-order low-pass filter was designed by using FilterPro,and its advantages were presented.Experimental results indicate that the multiple-triggered phenomenon is eliminated by using the hysteresis comparator designed,and the rise-time of output square wave falls to 108 ns from 1.66 μs as compared with that of a traditional opened-loop comparator.Furthermore,the 4th-order filter designed in this paper improves the linearity and sensitivity of the DC output,the linearity（R2） increases from 0.908 3 to 0.999 9,and the convention gain improves by 96.5％ as compared with that of the typical designs of amplifier/filter circuits.Moreover,the peak-to-peak value of the interference signal on a Low Pass Filter（LPF） DC output decreases from 50-230 mV to 10-20 mV,which reduces the phase detection error effectively.

关 键 词：激光测距系统 鉴相精度 迟滞比较器 整形模块 放大 滤波模块 

分 类 号：TN247[电子电信—物理电子学] TN713