A novel digital-to-analog conversion technique using duty-cycle modulation

The novel digital-to-analog conversion technique studied in this paper, is founded on the digital duty-cycle modulation principle. It consists of a simple digital duty-cycle modulation program loaded in the flash memory of a microcontroller and an external analog low pass filter. Both pulse width and modulation period, simultaneously evolve according to the variation of the modulating input. Then, under the proposed modulation technique, high frequency harmonics with rank greater than a number Nh, are significantly eliminated from the spectrum of the resulting modulated wave. As a merit, the digital modulated wave to be filtered is computed directly and very fast from its discrete Fourier series model. Thus, the related digital modulation and generation routines do not require an intermediary n-bit processing hardware logic. The predicted and experimental results obtained when testing a prototyping digital-to-analog conversion workbench driven by a PIC30F6014A microcontroller, are presented and compared. These results show the feasibility and high quality of digital-to-analog conversion via digital duty-cycle modulation. Keywords—Digital-to-analog conversion, digital duty-cycle modulation, fast Fourier series, analog filter, DsPIC30F6014A development kit.