A 99.5dB-DR 5kHz-BW Closed-Loop Neural-Recording IC based on Continuous-Time Dynamic-Zoom ΔΣ ADC with Automatic AFE-Gain Control

2021 IEEE Asian Solid-State Circuits Conference (A-SSCC) Pub Date : 2021-11-07 DOI:10.1109/A-SSCC53895.2021.9634824

Yoontae Jung, Soon-Jae Kweon, Hyuntak Jeon, Taeju Lee, Injun Choi, Kyeongwon Jeong, Mi Kyung Kim, H. J. Lee, S. Ha, M. Je

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引用次数: 1

Abstract

Neural-recording ICs have been a key tool to unravel the mystery of the human brain and find treatments for various neurological diseases. Since neural signals inherently have a small amplitude and suffer from environmental interferences, conventional neural recording circuits have been mainly designed for low noise, high CMRR, and low power, using the structure with a high-gain amplifier and a low-resolution ADC [1] (Fig. 1). With the advent of closed-loop neurotherapeutics, stimulation artifacts have been a notorious obstacle in neural recording. To tackle this issue, a direct-conversion structure has been widely used due to its wide dynamic range [3] –[7]. However, the structure could not meet the bandwidth (BW) requirement of 5kHz and the input-referred noise (IRN) requirement of $7 \mu V_{rms}$ simultaneously. In this paper, we present a closed-loop neural-recording IC using an adaptive automatic gain controller (AGC) and continuous-time dynamic-zoom $\Delta \Sigma$ ADC (CT-Zoom-ADC). By combining the AGC and CT-Zoom-ADC, the IRN performance is improved to $6.1 \mu V_{rms}$ at 5kHz BW, and the saturation issue of the conventional amplifier-based recording structure is alleviated. Also, the recording IC can rapidly recover the signal from transient artifacts thanks to the digital auto-ranging block (DAR).

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基于自动afe增益控制的连续动态变焦ΔΣ ADC的99.5dB-DR 5kHz-BW闭环神经记录IC

神经记录集成电路一直是解开人类大脑之谜和寻找各种神经系统疾病治疗方法的关键工具。由于神经信号固有的小振幅和受环境干扰，传统的神经记录电路主要设计为低噪声、高CMRR和低功耗，使用高增益放大器和低分辨率ADC的结构[1](图1)。随着闭环神经疗法的出现，刺激伪像已经成为神经记录的一个臭名昭著的障碍。为了解决这一问题，直接转换结构由于其宽动态范围而被广泛使用[3]-[7]。然而，该结构不能同时满足5kHz的带宽(BW)和$7 \mu V_{rms}$的输入参考噪声(IRN)要求。在本文中，我们提出了一个闭环神经记录IC使用自适应自动增益控制器(AGC)和连续时间动态变焦$\Delta \Sigma$ ADC (CT-Zoom-ADC)。通过将AGC与CT-Zoom-ADC相结合，在5kHz BW下将IRN性能提高到$6.1 \mu V_{rms}$，缓解了传统基于放大器的记录结构的饱和问题。此外，由于数字自动测距块(DAR)，记录IC可以快速从瞬态伪影中恢复信号。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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2021 IEEE Asian Solid-State Circuits Conference (A-SSCC)

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