Multi-Band Filters for Frequency Division Multiplexing networks in power line communications

In order to construct large networks in PLC system, FDM (frequency division multiplexing) or TDM (time division multiplexing) access scheme is often used. In general, the FDM is better solution for the systems which require real-time performance, but interference signals from adjacent sub-networks must be rejected by the analog filters to prevent the receiving sensitivity degradation of the desired signals. In this paper, a novel filter circuit, called ldquomulti-band filtersrdquo, is proposed to realize analog band-pass filter banks. The design method and the measurement results of the frequency characteristics of the multi-band filters are shown in this paper. By rejecting the interference signal with the multi-band filters, the equivalent SNR improvement of 10 dB is confirmed by data rate measurement.