Digital Pulse-Width-and-Density Modulator Based on Binary Counting

This study presents a digitally-controlled, combined pulse-width and pulse-density modulator (DPWDM) that leverages the inherent pulse width modulation associated to natural binary counting. The proposed approach involves combining the individual bit-counting pulses to synthesize a modulated signal where the mean voltage is directly proportional to the input digital code. A circuit design, based on general-purpose components, is proposed for an 8-bit digital-to-analog converter. The architectural concept is scalable, supporting resolutions that can accommodate any number of bits. The paper describes the simulations conducted to verify the proper functioning of the circuit and to evaluate its performance. Tests were performed to determine the static characteristic of the converter, measure its nonlinearity, and observe its step response. The circuit combines the benefits of both PWM and PDM modulations, offering a blend of energy efficiency with simplicity and better smoothing.