(A) high dynamic range neural recording system with automatic adaptive gain control utilizing dynamic zoom delta-sigma ADC

Abstract

Recently, closed-loop electrical stimulation has been one of the leading neurotherapeutic treatments for various neural disorders. The closed-loop electrical stimulation simultaneously records neural signals and stimulates the focus of the neural disease. The closed-loop stimulation has higher treatment efficiency and fewer side effects compared to open-loop stimulation

however, stimulation artifacts are applied to the neural signal and increase the requirements of the neural signal recording system design. In order to design the bidirectional neural interface, the neural recording system should meet the requirements of high dynamic range, low power consumption and sufficient bandwidth. There are many limitations that complicate satisfying all of these conditions using conventional neural recording topologies.

In this paper, automatic adaptive gain control with dynamic zoom $\Delta\Sigma$ ADC is proposed to overcome the limitations of the conventional topologies. The automatic adaptive gain controller adaptively changes the gain of an amplifier according to the input signal of the system and controls the over-sampling ratio of the zoom $\Delta\Sigma$ ADC clock. This optimizes SNDR and saves power consumption. The neural recording system was realized using 0.18 $\mu$m CMOS process. The system consumes minimal power (10.9 $\mu$W) and has peak SNDR performance of 77.3 dB, with an expanded input linear range.