大动态范围激光雷达时刻鉴别电路设计

Design of Time Discrimination Circuit for Large Dynamic Range LiDAR

摘要:

在激光雷达系统中,受限于被测目标距离及反射特性的变化,回波信号的峰值动态范围大,导致由恒比定时鉴别电路确定的回波到达时刻波动较大,产生的行走误差影响了系统的测距精度和测量范围。设计了一种带自适应增益控制的恒比定时鉴别电路,基于回波信号水平快速自动调节放大电路的增益,可适应较大动态范围下的目标测量。实验结果表明,采用自动增益与恒比鉴别电路相结合的方法设计的激光雷达时刻鉴别电路,可以基于回波信号水平在25ns的时间范围内实现放大电路增益的自适应调节；当输入信号上升时间为3ns、电压动态范围为29dB时,利用增益的自动控制可以将回波信号的动态范围降低至9dB,将回波时刻鉴别误差控制在0.42ns内,有效减小了测距系统的行走误差。

Abstract:

In the LiDAR system, due to the variation of the target distance and reflection characteristics, the peak value of the echo signal fluctuates in a relatively large range, which leads to a big fluctuation of the arrival time of the echo determined by the constant ratio timing discriminator circuit, and the resulting walking error affects the ranging accuracy and measurement range of the system. In this paper, a constant fraction discriminator with adaptive gain control is designed, thus the gain of the amplifier circuit can be adjusted quickly and automatically based on the level of the echo signal, which can adapt to the target measurement in a large dynamic range. The results illustrate that the designed circuit adopting automatic gain and constant fraction discriminator component is able to automatically configure and amplify the circuit gain within 25ns. When increasing duration of input signal to 3ns and the voltage dynamic range is stabilized around 29dB, the automatic control system adopted automatic gain design can effectively reduce the fluctuation range of dynamic error and the discrimination error of echo signal to 9dB and 0.42ns respectively, reducing the walking error significantly.