Dynamically reconfigurable FIR filter architectures with fast reconfiguration

This work compares two finite impulse response (FIR) filter architectures for FPGAs for which the coefficients can be reconfigured during run-time. One is a recently proposed filter architecture based on distributed arithmetic (DA) and the other is based on a LUT multiplication scheme. Instead of using the common internal configuration access port (ICAP) for reconfiguration which is able to change the logic as well as the routing, it is sufficient to reconfigure only the logic in the regarded architectures. This is realized by using the configurable look-up table (CFGLUT) primitive of Xilinx that allows reconfiguration times which are orders of magnitudes faster than using ICAP. The resulting FIR filter architectures achieves reconfiguration times of typically less than 100 ns. They can be reconfigured with arbitrary coefficients that are only limited by their length and word size. As their resource consumptions depend on different parameters of the filter, a detailed comparison is done. It turned out that if the input word size is greater than approximately half the number of coefficients, the LUT based multiplication scheme needs less resources than the DA architecture and vice versa.