A 16-bit Encrypted On-chip Embedded System for Implantable Medical Devices

A 16-bit on-chip embedded encryption system built upon eFUSE, cipher, hash functions, and EDCs for optical nerve stimulation is presented. The foundry-provided eFUSE IP is modified with a one-shot block to support wireless power transfer operation by mitigating the supply voltage drop problem during sensing to avoid subsequent resetting. Novel logic gate-based auxiliary circuit facilitates different sensing and programming modes in eFUSE. A 128-bit cipher is reduced to 16 bits with cascade structure using the proposed divide-and-conquer algorithm, keeping the cipher strength constant. The developed resource sharing technique reduces the area and the power consumption of the ciper circuits by 2.7 times and 5.1 times, respectively. The whole system with the optical nerve simulator is fabricated with 0.18$\mu$m BCDlite process, and measurement results show the correct encryption operation when powered by wirelessly transferred power.