中文摘要：

利用高速运放和比较器实现输入弱小信号的放大及整形,采用FPGA完成对输入信号的精确频率测量.测量范围为1Hz～100MHz,内部分成5个量程,可根据输入信号频率不同自动进行量程切换,并支持对方波的占空比及双通道同源方波时间间隔测量等功能.FPGA测量结果经MCS-51单片机处理后送至LCD完成显示,测量相对误差不大于10-4,可用于各类低成本数字测量仪器研发.

英文摘要：

High-speed amplifier and comparator were adopted to complete waveform amplifying and reshaping.With FPGA as processing core,accurate frequency measurement of input signal can be obtained.5measurement scales were divided to support 1 Hz～100 MHz frequency measurement internally.Automatic scale switch was implemented,too.Furthermore,duty measurement of square wave,and time interval analysis of 2homologous square wave all supported.MCS-51 microcontroller was utilized to complete final result calculation using FPGA＇s original measurement data,and these results were displayed via LCD.Corresponding relative measurement error was less than 10-4.Presented design can be used for low-cost digital frequency meter design.