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Session: Poster session 2 (Odd numbers)
Session starts: Friday 27 January, 10:00
Presentation starts: 10:00

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Francesc Varkevisser (Delft University of Technology)
Tiago L. Costa (Delft University of Technology)
Wouter A. Serdijn (Delft University of Technology)

Abstract:
The development of neuroprosthetic bioelectronic devices requires implantable stimulator systems with hundreds to thousands of output channels [1]. Typically, these devices are powered wirelessly, which leads to limited available power. Therefore, power efficiency optimization is crucial to facilitate as many output channels as possible. Current-mode electrical stimulation is favored over voltage-mode stimulation because of its inherent control over the charge injected into the tissue, which is important for safety. However, the voltage drop over the current driver leads to power losses, especially in multichannel stimulators. An adaptive voltage supply can reduce overhead losses and increase power efficiency [2]. Still, due to area constraints, providing channel-specific adaptive voltage supplies in large-scale multichannel systems remains challenging. Moreover, conventional power management implementations use multiple conversion stages, which leads to cascaded losses and low total conversion efficiency [3]. This work proposes a parallel, adaptive ac/dc power management strategy for generating channel-specific adaptive voltage supplies. A phase-controlled adaptive ac/dc converter is designed that converts the incoming power signal to the appropriate voltage level in a single stage, preventing cascaded losses. Multiple converters are employed in parallel to generate channel-specific voltage levels to increase the power efficiency at each output channel. The proposed implementation requires less area and offers better scalability than the alternative approach of switched-capacitor dc/dc converters. The power management design will be combined with current-mode stimulator circuits to develop a large-scale, power-efficient multichannel system for neuroprosthetic applications. [1] Fernández, E., Alfaro, A., & González-López, P. (2020). Toward Long-Term Communication With the Brain in the Blind by Intracortical Stimulation: Challenges and Future Prospects. Frontiers in Neuroscience, 14(August). [2] Lee, H.-M., Park, H., Ghovanloo, M. (2013). A Power-Efficient Wireless System With Adaptive Supply Control for Deep Brain Stimulation. IEEE Journal of Solid-State Circuits, 48(9), 2203–2216. [3] Kim, C., Ha, S., Park, J., Akinin, A., Mercier, P. P., & Cauwenberghs, G. (2017). A 144-MHz Fully Integrated Resonant Regulating Rectifier with Hybrid Pulse Modulation for mm-Sized Implants. IEEE Journal of Solid-State Circuits, 52(11), 3043–3055.