A wirelessly powered implantable stimulator device includes one or more antenna configured to receive an input signal non-inductively from an external antenna, the input signal containing (i) electrical energy to operate the implantable stimulator device and (ii) configuration data according to which a pulse-density modulation (PDM) encoded stimulus waveform signal is retrieved to synthesize a desired stimulation waveform; a circuit coupled to the one or more antenna; and one or more electrodes coupled to the circuit and configured to apply the desired stimulation waveform to neural tissue, wherein the circuit is configured to: rectify the input signal received at the one or more antennas non-inductively; extract the electrical energy and the configuration data from the input signal; and in accordance with the extracted configuration data, retrieve the pulse-density modulation (PDM) signal to synthesize the desired stimulation waveform therefrom.