Economic implementation of a high performance FDM system using the sequence discriminator
An economic design approach to high-selectivity single-sideband modulation and demodulation using a polyphase network sequence discriminator is presented. The tolerance requirements on capacitors to manufacture the circuits have been relaxed to a practical value of +or-1.0% from the existing state of the art of +or-0.2% through the introduction of a new trimming procedure, which can be used for other circuit designs. New circuits using the buffered polyphase network are proposed. The circuits use capacitors of the same nominal value, which simplifies the manufacture of the filter. These circuits allow image band rejection in excess of 62 dB and a passband ripple less than +or-0.25 dB with +or-1.0% capacitors. The filters were manufactured on a 1-in*2.5-in substrate using thick-film technology. The overall yield of the manufactured network is close to 100%.<<ETX>>