A QAM modulator for WCDMA base station

A QAM modulator has been developed and implemented with programmable logic devices (PLDs). D/A converters were implemented in 0.5 /spl mu/m CMOS technology. A conventional QAM modulator needs four multipliers, two adders and sine/cosine ROMs. The designed CORDIC based QAM modulator has about same logic complexity as two multipliers and an adder with the same word sizes. The QAM modulator accepts 12 b in-phase and quadrature data streams, interpolates them by 16 and upconverts the baseband signal to a selected center frequency. The QAM modulator is designed to fulfil the spectrum and error vector magnitude (EVM) specifications of the wideband code division multiple access (WCDMA) system.