A digital waveform synthesizer, using a direct digital synthesizer and a digital frequency divider. The direct digital synthesizer provides a digitally synthesized input frequency signal. An upconverter and frequency divider circuit upconverts and divides the synthesized input frequency signal to provide an divided synthesized frequency signal. An output upconverter circuit is coupled to the upconverter and divider circuit for providing an upconverted output frequency signal. A reference frequency generator is coupled to the direct digital synthesizer, to the upconverter and divider circuit, and to the output upconverter, for providing clock and frequency reference signals thereto. The waveform generator is coupled to the direct digital synthesizer for commanding a desired waveform. The frequency divider is used to improve the inherently poor spurious signal performance of the direct digital synthesizer. The digital waveform synthesizer provides fast switching, flexible and precisely defined frequency output signals. The digital waveform synthesizer may be used with any signal generator that requires high spectral purity and frequency precision, but requires relatively narrow signal bandwidth.