A RISC-V Based Medical Implantable SoC for High Voltage and Current Tissue Stimulus

A RISC-V based System on Chip (SoC) for high voltage and current tissue stimulus, targeting implantable medical devices, is presented. The circuit is designed in a 0.18μm HV-CMOS process, including the RISC-V 32RVI based microcontroller core, called Siwa -which includes SPI, UART and GPIO interfaces, a packet-based bus and memory controller, and 8kB SRAM-, combined with several biological tissue stimulus and sensing circuits. The complete test chip (analog+RISC-V) occupies a 5mm² area but only 0.82mm² correspond to the RISC-V micro-controller, which operates up to 20MHz, with average energy needs of less than 48 pJ/cycle (3pJ STD), and for which several reliability and safety issues were considered.