Architecture of the developed circuit prototypes for the microstimulators.

The dashed red line represents the flow of stimulating (half-wave) rectified current when control signal 1 (CS1) activates the current source 1. If no current source is active, the switch (SW) closes and the alternating current (AC) picked-up by the muscle electrodes flows through the regulation subcircuit to power up the rest of the electronics. A demodulation subcircuit is used to extract information from the HF bursts, and a burst trigger is used to wake up the control unit when it is asleep in-between “Stimulation bursts”.