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A VLSI implementation of an all-digital frequency-agile single-chip quadrature amplitude modulation (QAM) modulator is presented. The proposed chip supports wide variety data rates with diversity in spatial and frequency domain suitable for a wireless modem. The QAM modulator accepts either a parallel or serial bit stream input and assigns these to various QAM symbol formats for transmission. An optimized architecture for the variable modulator supports QAM symbol rates from 6 kBaud to 8.75 MBaud continuously and digitally-flexible IF frequencies up to 70 MHz with four channel beamforming diversity.
Cho et al. (Thu,) studied this question.