Design of fourth-order IIR digital filter based on FPGA

The IIR filter is a widely used digital signal processing component, which can be roughly classified into direct type, cascade type and parallel type. The IIR filter coefficients are designed by using MATLAB Buffer function, and implemented on the FPGA using Verilog language. The circuit is composed of several second-order filter cascades. When the sampling frequency is 44. 1KHz, the cut-off frequency of the passband is KHz, and a sine wave of 1KHz+3KHz is input. After different types of IIR filters, a KHz sine wave is output and passed. Visual graphical and hardware waveform results are simulated by MATLAB and Modelsim respectively.