Auto-ranging DSM-ADC and LED Communication for Whole-life Neural Recording Module

Abstract

This paper focused on establishing a closed-loop stimulation environment capable of accommodating multiple experimental animals. The key requirement for closed-loop stimulation is the ability to measure neural signals within the stimulation environment. To achieve simultaneous measurement of stimulation artifacts in the range of tens of mV and neural signals in the range of hundreds of V, a recording system with a large dynamic range is essential to prevent saturation caused by the high-intensity stimulation artifacts. Furthermore, to transmit the acquired data externally, down-sampling is essential to reduce power consumption. In this work, delta-sigma (DS) modulation and digital prediction techniques are used to ensure a high dynamic range and prevent saturation in the recording stage. Additionally, to facilitate the simultaneous transmission of data from multiple animals without signal degradation, an internal cascaded integrator-comb (CIC) filter is utilized to encode the down-sampled data. The proposed approach enables the creation of a robust closed-loop stimulation recording system capable of handling multiple subjects while maintaining data integrity. We present 8 channel neural recording chip with a 65-nm CMOS process and the entire chip area is 1 mm2. Two signals were transmitted and received at a distance of 10 cm with a 1 Mbit data rate without an error.