An 8-Channel Bidirectional Neurostimulator IC with a Highly-Linear High-Dynamic-Range ADC-Direct Architecture for Simultaneous Recording and Stimulation

Abstract

This thesis presents the design, implementation, and validation of an 8-channel bidirectional neurostimulator IC with a highly-linear high-dynamic-range ADC-direct architecture for simultaneous recording and stimulation. Each channel hosts a novel highly-linear high-dynamic-range recording architecture capable of amplification and quantization of brains neural signals in the presence of large differential-mode and common-mode stimulation artifacts, as well as a fully-programmable 8-bit current-mode electrical stimulator. The architecture enables the possibility of a patient-specific stimulation therapy required for the next generation of implantable closed-loop neuro-stimulators used for treatment of various neurological disorders. The proposed design adopts an ADC-direct architecture employing a dual-loop SAR-assisted continuous-time delta-sigma ADC architecture for differential-mode stimulation artifacts and offset removal. The presented channel achieves a high input impedance (1.8 G at 1 kHz), 400 mV linear input signal range, 94 dB dynamic range, and consumes 4.6 W with a signal bandwidth of 5 kHz.