This paper presents a single-stage single-coil wireless multi-channel adiabatic supply stimulation (M-CASS) system that generates four separate adiabatic supplies to independently regulate four constant stimulus currents, without using power-hungry current sources, regardless of stimulus current and load impedance. A wireless power distributor, combined with an AC-DC quadruple-output current regulator, independently controls four stimulus channels while receiving AC power from a single wireless link. A channel-optimized size control technique and a wide adaptive offset control scheme are employed to enhance the peak AC-to-stimulation efficiency in wireless adiabatic stimulation. The 2.72 mm2 0.25-μm CMOS M-CASS demonstrates four independently controlled stimulus currents with four adiabatic supplies over a 6.78-MHz resonant link. Furthermore, M-CASS achieves a peak AC-to-stimulation efficiency of 82.2% when steering four 2-mA currents and maintains approximately 80% efficiency even when the four channels experience different impedances and currents. These features of M-CASS using a single coil provide a compact and energy-efficient solution for multiple-source current-steering (MSCS) deep brain stimulation (DBS) applications.
Lee et al. (Thu,) studied this question.