This invention relates to waveform generators and more particularly to waveform generators to generate COS(w.sub.o + w.sub.m)t, SIN(w.sub.o + w.sub.m)t, COS(w.sub.o - w.sub.m)t and SIN(w.sub.o - w.sub.m)t waveforms.
In the past waveform generators to produce the above-mentioned waveforms included multiple sine wave generators locked to a frequency standard by phase locked loops to form the appropriate sine and cosine waveforms.
The shortcomings of the prior art waveform generators is that the circuitry is analog and more complicated, there are inherent errors in maintaining the current phase relationship and there are problems in switching frequency.