基于FPGA的模拟信号FFT实现

Implementation of FFT of Analog Signals on FPGA

介绍一种基于FPGA的模拟信号的快速傅里叶变换实现方法。首先由AD9280及偏置电路对输入模拟信号进行衰减和采样,然后在FPGA内部实现基于FFT IP核的1024点FFT,控制时序由VHDL语言编程产生,FFT输出结果经过计算得到频谱信息。可以用输入实际模拟信号,嵌入式逻辑分析仪实时采集FFT输出数据,验证设计的正确性,也可以用后续进行IFFT和D/A验证设计的正确性。文章用后者在ALTERA公司的DEII板上验证了设计的正确性。

A fast Fourier transform method for analog signals based on FPGA is introduced.First,the input analog signals are attenuated and sampled by AD9280 and bias circuits.Then,the 1024 point FFT based on FFT IP core is implemented inside FPGA.Control timing is generated by programming in VHDL language.The spectrum information can be calculated by the output of FFT.In order to verify the correctness of the design,the real-time FFT output data can be collected by the embedded logic analyzer with the input of the actual analog signal.An analog signal with a single frequency is input to the circuit.Another way is to carry out subsequent IFFT transform and A/D circuits to restore the original signal.The latter method is adopted in the DE II board.