FPGA Implementation of a Configurable Complex Blind Adaptive Equalizer

This paper discusses the design and field programmable gate array (FPGA) implementation of a complex 18- tap blind adaptive equalizer, which can be utilized in the development of quadrature amplitude modulation (QAM) based demodulators for cable modems. The design can be configured to achieve channel equalization for square QAM signals up to 256-QAM by means of the constant modulus algorithm (CMA), multimodulus algorithm (MMA), radius-adjusted modified-multimodulus algorithm (RMMA), and radius-adjusted multimodulus decision- directed algorithm (RMDA). The implementation operates at a maximum symbol frequency of 8.055 MBaud, which is comparable to recent QAM equalizer designs for cable modems.