Redundant Crossfire: A Technique to Achieve Super-Resolution in Neurostimulator Design by Exploiting Transistor Mismatch
Redundant Crossfire: A Technique to Achieve Super-Resolution in Neurostimulator Design by Exploiting Transistor Mismatch
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DOI：
10.1109/jssc.2021.3057041
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发表时间：
2021-08-01
影响因子：
5.4
通讯作者：
Yang, Zhi
中科院分区：
文献类型：
--
作者：
Anh Tuan Nguyen;Xu, Jian;Yang, Zhi
高分辨率神经刺激器是许多双向神经接口的重要组成部分。在实践中，完全集成的神经刺激器设计的有效分辨率通常受到晶体管失配的阻碍，特别是在亚微米CMOS工艺中。在这篇文章中，我们提出了一种新的电路技术，称为冗余交火（RXF），以解决这一挑战。它是来自我们的冗余传感（RS）框架，其目的是在工程信息冗余到系统架构，以提高其有效的分辨率。RXF涉及组合（即，交叉激发）两个或更多个电流驱动器的输出以形成冗余结构，当适当配置时，该冗余结构可以产生具有超出物理约束通常允许的限制的有效超分辨率的精确电流脉冲。与以往的任何工作，所提出的技术实现了高精度直接利用随机晶体管失配与过大的失配比为10%-20%。RXF的有效性通过Monte Carlo模拟和完全集成的神经刺激器芯片的测量结果进行了验证。该刺激器配备了一个5位电流数模转换器（IDAC）和两个4位电流倍增器，在1.1 mA全量程内实现了9.75位的有效分辨率。所制造的芯片的应用是通过外周神经向人类截肢者递送神经反馈，其中刺激脉冲的幅度被精确地控制以编码触觉响应的强度。
A high-resolution neurostimulator is the essential component of many bidirectional neural interfaces. In practice, the effective resolution of fully integrated neurostimulator designs is often hindered by the transistor mismatch, especially in submicrometer CMOS processes. In this article, we present a new circuit technique called redundant crossfire (RXF) to address this challenge. It is derived from our redundant sensing (RS) framework, which aims at engineering information redundancy into the system architecture to enhance its effective resolution. RXF involves combining (i.e., crossfiring) the outputs of two or more current drivers to form a redundant structure that, when properly configured, can produce accurate current pulses with an effective super-resolution beyond the limitation commonly permitted by the physical constraints. Unlike any previous works, the proposed technique achieves high-accuracy by directly exploiting the random transistor mismatch with an excessively large mismatch ratio of 10%-20%. The effectiveness of RXF is verified through both Monte Carlo simulations and measurement results of a fully integrated neurostimulator chip. Equipped with a 5-bit current digital-to-analog converter (IDAC) and two 4-bit current multipliers, the stimulator achieves an effective resolution of 9.75 bits in a 1.1-mA full range. An application of the fabricated chip is to deliver neuro-feedback to a human amputee through peripheral nerves where the amplitude of stimulation pulses is accurately controlled to encode the tactile response's intensity.