A viterbi decoder/modulator ASIC for up band CDMA PCS base station

摘要

A high speed Viterbi decoder (VD) and modulator ASIC for a base station in up band DS-CDMA-PCS has been developed using 0.35 mu m CMOS technology with 210 K gates. For VD, eight add-compare-select units are used for reducing the decoding time. Full decoding depth is used in VD to get the better coding gain. The modulator block is designed to perform transmitter function of 8 forward CDMA channels. According to J-STD-008 standard, the symbol energy shall have four different values according to symbol rate and so a baseband filter should support at least 4 different is used for this requirement. Baseband filter is most complex block in forward CDMA channel processing and shared with 8 channels for chip area reduction.