Abstract: A tunable digital modulator is tunable across an R.F. frequency range for transmission without additional frequency conversion and includes two toggled multiplexed analog-to-digital converters for reducing spurious frequency components in the output. The modulator and digital-to-analog converters are fabricated in a single integrated circuit with the two converters laid out physically in adjacent spaces with their gain and voltage characteristics matched. By alternating the two digital-to-analog converters in producing the analog modulated signal output, transients from switching of the converters have a chance to die out before the output of each converter is sampled. Thus, any spurious glitch energy is greatly attenuated.