An Efficient Distributed Arithmetic-Based Realization of the Decision Feedback Equalizer

A distributed arithmetic (DA)-based decision feedback equalizer architecture for IEEE 802.11b PHY scenarios is presented. As the transmission data rate increases, the hardware complexity of the decision feedback equalizer increases due to requirement for large number of taps in feed forward and feedback filters. DA, an efficient technique that uses memories for the computation of inner product of two vectors, has been used since DA-based realization of filters can lead to great computational savings. For higher-order filters, the memory-size requirement in DA would be high, and so ROM decomposition has been employed. The speed is further increased by employing digit-serial input operation. Two architectures have been presented, namely the direct-memory architecture and reduced-memory architecture where the later is derived using the former. A third architecture has also been presented where the offset-binary coding scheme is employed along with the ROM decomposition and digit-serial variants of DA. Synthesis results on Altera Cyclone III EP3C55F484C6 FPGA show that the proposed DA-based implementations are free of hardware multipliers and use less number of hardware resources compared to the multiply-and-accumulate-based implementation.