文档介绍：简易频率特性测试仪(E题)
摘要: 该简易频率特性测试仪采用STM32F103ZET6核心板,主要由自制正交扫描信号源、RLC被测网络、乘法器、低通滤波等功能模块组成;测试数据包含信号的幅频特性及相频特性,于彩屏TFT上显示。本系统利用高速DDS(AD9854)模块实现信号发生电路,能输出双端口的正交信号,并可控制设置其幅值与频率。
被测网络采用RLC串联谐振电路,达到要求的网络通带中心频率。将DDS产生的正交信号和被测网络信号通过乘法器AD835模块,经LTC1564低通滤波,利用单片机上的片上AD进行采样,最终在彩屏上显示输出,完成对信号的幅频和相频的简单测试。
关键词: STM32;DDS;乘法器;滤波;TFT
Abstract: The simple frequency tester is based on high-performance STM32F103ZET6 controller, and it mainly consists of self-maid signal generator, work, multipliers, low-pass filter and other function blocks. The test data contains amplitude-frequency characteristics and phase-frequency characteristics, and will be displayed on TFT. The system uses high-speed DDS (AD9854) block as signal circuit, generating the dual-port quadrature signals, whose amplitude and frequency can be controlled and set. The work is made of RLC circuit, which is able to achieve the standardized center frequency. The quadrature signals generated by DDS and the signals under test pass through the multiplier AD835 and the LTC1564 low-pass filter, and will be sampled by the 12-bit on-chip ADC. The final output is displayed on the TFT plete the test of amplitude-frequency and phase-frequency.
Keyword: STM32; DDS; multiplier; filter; TFT
一、方案选择与论证·······································3
正交扫频信号源的设计与选择·································3
乘法器模块的设计与选择·····································3
低通滤波器的设计与选择·····································3
ADC 模块的设计与选择·······································3
被测网络的设计与选择·······································4
二、电路设计·············································4
正交扫描信号源设计电路·····································4
模拟乘法器设计电路·········································4
低通滤波器设计电路·········································4
末级电压抬升设计电路·······································5
三、系统设计·············································5
方案总体设计描述···········································5
理论分析与计算······························