A 3.3V Saturation-Aware Neurostimulator with Reset Functionality in 22 nm FDSOI

Neurostimulation and extensive signal processing are requirements for closed-loop neural interfaces. At the same time, issues of thermal biocompatibility limit the power budget in such applications, driving the trend towards small technologies like 22 nm FDSOI. While overcoming aforementioned constraints, this trend complicates the design of current stimulators with up to 3. 3V supply voltage in such technology. Stacking of 1.8 V compliant IO-transistors, is part of the solution. In this work we address this challenge, showcasing a small footprint neurostimulator design (0.0128 $mm^{2}$) in 22 nm FDSOI, capable of detecting source saturation, a safe reset state and the generation of arbitrary multi-channel stimulation waveforms. The DNL and INL of the output current are in the range of ±0.45 LSB and ±2.2 LSB respectively. The output current range of ±186$\mu \mathrm{A}$ is divided into 63 steps.