A digital modulator VLSI covering various modulation techniques and wide range data speeds

The authors describe the techniques and the 6 K CMOS gate-array VLSI implementation used to design a digital modulator for radio communications which is widely applicable to satellite communications. The modulator generates a constant carrier frequency for various data transmission speeds using the interpolation technique. The modulator can be readily applied to various modulation schemes, by changing ROM contents. The techniques discussed are useful for standardizing circuit blocks and for utilizing modulators flexibly. The performance of the VLSI is evaluated, and the experimental results are presented. It is shown that the VLSI array is compatible with eight data speeds from 2.4 to 128 kb/s