Pulse-density modulation to synthesize stimulation waveforms on an implantable device

A wirelessly powered implantable stimulator device, the wirelessly powered implantable stimulator device comprising:

• one or more antennas configured to receive an input signal through a non-inductive coupling from an external antenna on an external controller, the input signal containing
• (i) electrical energy to operate the wirelessly powered implantable stimulator device, and
• (ii) configuration data including parameters for generating a specific stimulus waveform;
• a circuit coupled to the one or more antennas and including a memory device that stores a digital representation of a PDM encoded signal for generating the specific stimulus waveform, a clock, an oscillator device, and a H bridge electrode driver;
• and
• one or more electrodes coupled to the circuit and configured to apply the specific stimulus waveform to neural tissue,
• wherein the circuit is configured to:
• rectify the input signal received at the one or more antennas through the non-inductive coupling from the external controller;
• extract the electrical energy and the configuration data from the rectified input signal;
• and
• based on the parameters in the extracted configuration data, (i) select the digital representation of the PDM encoded signal as stored on the memory device of the circuit and (ii) control the oscillator device of the circuit to signal the clock to clock the PDM encoded signal and convert the digital representation of the PDM encoded signal using the extracted electrical energy such that the specific stimulus waveform is generated by the H bridge electrode driver for applying stimulation at the one or more electrodes by using the extracted electrical energy.