【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。更多还原

【Abstract】 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 comparator 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 108ns from 1.66μs 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 50-230mV to 10-20mV,which reduces the phase detection error effectively.更多还原