Infinite Impulse Response Filter Structures in Xilinx FPGAs

A large percentage of filters implemented in the digital domain are Finite Impulse Response (FIR) filters. These filters are used over a wide range of sample rates and are well supported in terms of tools, software, and IP cores. Another type of digital filter is the Infinite Impulse Response (IIR) filter, which tends not to be so well supported and is generally used in the lower sample rates. The IIR filter, known as a recursive filter, uses feedback to compute outputs.

This paper discusses the various kinds of IIR filters and structures, and, with the use of The MathWorks tools, shows how these structures can be mapped to the Xilinx FPGA architecture.