一种高精度频率测量电路设计  

Design of high precision frequency measurement circuit

作　　者：谢尚豪 张硕 许波 Xie Shanghao;Zhang Shuo;Xu Bo(Sichuan Jiuzhou Electrical Group Limited Liability Company,Mianyang 621000,China;College of Automation Engineering,University of Electronic Science and Technology of China,Chengdu 611731,China)

机构地区：[1]四川九洲电器集团有责任限公司,绵阳621000 [2]电子科技大学自动化工程学院,成都611731

出　　处：《电子测量技术》2018年第18期115-121,共7页Electronic Measurement Technology

摘　　要：为了满足一种多功能便携式示波记录仪的多种可插拔采集测量模块的特点,设计出一种高精度频率测量电路模块。采用测周期法测得信号的周期,从而间接计算出信号的频率、占空比、脉宽等参数。主要分为模拟通道和数字处理电路两个部分。模拟通道将信号经过适当的增益变换后,通过一个二阶低通滤波电路,根据用户需要进行低通滤波,将滤波后的信号整形为矩形信号,然后送入数字处理部分。数字处理电路采用FPGA作为主控制器,完成对矩形信号的周期测量,频率、占空比等参数的计算,对模拟通道的控制以及与上位机的通信。制作出的实物电路经过调试后,设想的带宽限制、频率测量等功能均能良好实现,输入信号频率在0.01 Hz～200 kHz范围,峰值在±1～±50 V范围内,测频分辨率达到50 ns。In order to meet the characteristics of multiple pluggable acquisition and measurement modules of a multifunctional portable oscillograph, a high precision frequency measurement circuit module was designed. The circuit module uses the cycle method to measure the signal cycle, which indirectly calculates the signal frequency, duty cycle, pulse width and other parameters. There are two main parts： analog channels and digital processing circuits. The analog channel transforms the signal after appropriate gain conversion, passes through a second-order low-pass filter circuit, performs low-pass filtering according to the user＇s needs, and shapes the filtered signal into a rectangular signal, which is then sent to the digital processing section. The digital processing circuit uses FPGA as the main controller to complete the cycle measurement of the rectangular signal, the calculation of the frequency, duty cycle and other parameters, the control of the analog channel and the communication with the host computer. The module has two measurement channels and uses magnetic isolation to isolate the analog channels from the digital processing section. Create physical circuit after debugging, imagine the bandwidth limitations, frequency measurement, all can good implementation, the input signal frequency in the 0.01 Hz～200 kHz range, the peak within ±1～±50 V, frequency measuring resolution up to 50 ns.

关 键 词：频率测量 测周期法 模拟通道 FPGA 高精度 示波记录仪 

分 类 号：TP2[自动化与计算机技术—检测技术与自动化装置]