Abstract
In this paper we present a reconfigurable, step-up switched- capacitor DC-DC converter conceived to handle without efficiency penalty the wide range and sudden input voltage variations that characterize implantable medical devices supplied by a wireless power transfer system (WPT). In particular, we target the specifications of an implantable neural stimulator for retinal prosthetics supplied by a WPT based on an inductive link. We propose an original design methodology based on a model to estimate a priori the input voltage range and thus the set of required conversion ratios, and a procedure that, taking into account the switches conduction and driving losses, allows to derive the absolute switch size that maximizes the reconfigurable SCC overall efficiency. The SCC is designed in a commercial CMOS technology using a reduced number of external components to implement the flying and load capacitors. A thorough set of post-layout simulations shows that the converter is capable of dynamic self-reconfiguration and self-regulation over the whole 1.3–3.3 V input voltage range, achieving the desired 5 V output voltage with an efficiency between 57 and 74%.
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The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.
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Acknowledgements
This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI19C1093) and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT(NRF-2017R1A5A1015596).
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Kim, J., Marin, G., Seo, JM. et al. A 13.56 MHz reconfigurable step-up switched capacitor converter for wireless power transfer system in implantable medical devices. Analog Integr Circ Sig Process 110, 517–525 (2022). https://doi.org/10.1007/s10470-022-01990-8
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DOI: https://doi.org/10.1007/s10470-022-01990-8