一种数字频率特性测试仪的设计  

Design of a digital frequency characteristic analyzer

作　　者：孟瑞丽[1] 宋安[1] 张宏群[1] 尤天羽 刘恒[1] 

机构地区：[1]南京信息工程大学电子与信息工程学院,南京210044

出　　处：《南京信息工程大学学报（自然科学版）》2015年第2期137-141,共5页Journal of Nanjing University of Information Science & Technology（Natural Science Edition）

基　　金：江苏省自然科学基金(BK20131001);江苏省高校自然科学研究基金(13KJB510017);制造过程测试技术-省部共建教育部重点实验室开放基金(14ZXZK02)

摘　　要：设计了一种基于正交调制原理的数字频率特性测试仪,系统用稳态响应法测量电路的频率特性.单片机作为主控芯片,完成系统的总体控制及数字信号处理;使用集成的直接数字频率合成芯片输出全频率范围内的正弦波.系统对待测电路的输入信号及其输出响应采样,经数字信号处理后,获得电路的幅频特性和相频特性.设计的测试仪测某RLC网络,中心频率的相对误差小于0.2%,有载品质因数相对误差小于1.25%,最大电压增益大于-1 d B.频率特性测试仪输入输出阻抗均为50Ω,幅频误差绝对值小于0.5 d B,相频误差绝对值小于3°,测试仪能满足微机械谐振传感器特征参数测试需求.A digital frequency characteristic analyzer based on orthogonal modulation principle is developed using steady-state response measurement method.The frequency response analyzer consists of Direct Digital frequency Syn-thesis（DDS）,analog multiplier,low pass filter,and low power consumption MCU.The MCU is employed as main control unit to carry out overall control and digital signal processing.The sine wave over the full frequency range is output through the integrated DDS chip.The analyzer system samples and digitalizes the input signal and output re-sponse,hence the amplitude and phase frequency characteristics are obtained.An RLC network is chosen to test the frequency characteristic analyzer.Measurement results show that the center frequency error is not more than 0-2%, the absolute value of quality factor error is less than 1-25%,and the maximum voltage gain is larger than -1 dB. Both the input and output impedance of the frequency characteristic analyzer are 50 Ω,and the absolute value of measurement errors are less than 0-5dB and 3 ° for amplitude frequency and phase frequency,respectively.The ana-lyzer is suitable for characteristic parameter measurement of micromechanical resonant sensor.

关 键 词：直接数字频率合成(DDS) 正交 幅频曲线 相频曲线 

分 类 号：TN911.23[电子电信—通信与信息系统]