SINEWAVE MODULATION FOR DATA COMMUNICATION BY DIRECT DIGITAL SYNTHESIS AND SIGMA-DELTA TECHNIQUES

Direct digital synthesis and sigma-delta techniques have been proposed in recent years to realize sinewave generators and modulators for dat a communication. This paper explains the basic principles behind these techniques and presents schemes which implement popular modulation me thods such as frequency shift keying, phase shift keying and amplitude modulation. The schemes are mostly implemented with digital circuits. They ensure a high degree of flexibility and are fully compatible wit h VLSI integration technologies. Experimental results obtained on inte grated semicustom devices have demonstrated the validity of this appro ach.