Quantum Digital-to-Analog Converters (DACs) based on programmable Josephson array (PJVS) represent the most widely used quantum standard in ac voltage calibrations. The extension of PJVS frequency above the kHz range appears to be arduous, yet some enhancement are still practicable. In this work we demonstrate the possibility to advantageously operate a conventional binary-divided PJVS array with a reduced number of bias lines. This feature is achieved by exploiting both first and second Shapiro steps along with non-conventional DAC codings. Two newly devised bias techniques are described in detail and preliminary experimental tests on waveform synthesis have been carried out and are presented here.