This article presents a bio-impedance (bioZ) readout IC featuring a complex-domain noise-correlated baseline cancellation to overcome the limitation of the conventional baseline cancellation with the real-domain noise correlation. The proposed technique is especially beneficial in cases with significant phase shifts between the excitation current from the current generator (CG) and the input voltage signal produced across the bioZ, through which the CG current flows. This technique employs a tunable reference impedance (TRI) and adaptively adjusts it to match the bioZ in both magnitude and phase, thereby achieving a complex-domain correlation of CG noise. By flowing an identical CG current through both the TRI and bioZ, the noise voltages across the TRI and bioZ caused by the CG current become closely correlated with each other, even in the presence of substantial phase shifts, enabling effective CG noise removal after baseline subtraction. Furthermore, this work proposes a differential-difference current-balancing instrumentation amplifier (DD-CBIA) with quiet chopping for baseline subtraction, offering low power consumption, wide input range, and low input-dependent noise. Measurement results demonstrate significant enhancements in noise performance by a factor of 2.47 and 4.88 for the bioZs with phases of 30° and 60°, respectively, achieving a signal-to-noise ratio (SNR) of 101.5 dB and a figure of merit (FoM) of 150.0 dB. Validation through human-subject experiments using two-electrode configurations on the chest and wrist further supports the effectiveness of the proposed bioZ readout IC.

中文翻译：

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具有复域噪声相关基线消除功能的生物阻抗读出 IC


本文介绍了一种生物阻抗 （bioZ） 读出 IC，该 IC 具有复域噪声相关基线消除功能，以克服传统基线消除与实域噪声相关的限制。在电流发生器 （CG） 的激励电流与 CG 电流流经的 bioZ 上产生的输入电压信号之间存在显著相移的情况下，所提出的技术特别有用。该技术采用可调谐参考阻抗 （TRI） 并自适应调整它以在幅度和相位上匹配 bioZ，从而实现 CG 噪声的复域相关性。通过使相同的 CG 电流流过 TRI 和 bioZ，由 CG 电流引起的 TRI 和 bioZ 两端的噪声电压变得彼此密切相关，即使在存在大量相移的情况下也是如此，从而在基线扣除后能够有效地去除 CG 噪声。此外，这项工作还提出了一种差分电流平衡仪表放大器 （DD-CBIA），具有用于基线减法的安静斩波，具有低功耗、宽输入范围和低输入相关噪声。测量结果表明，相位为 30° 和 60° 的 bioZ 的噪声性能分别提高了 2.47 倍和 4.88 倍，信噪比 （SNR） 为 101.5 dB，品质因数 （FoM） 为 150.0 dB。通过在胸部和手腕上使用双电极配置进行人体实验进行验证，进一步支持了所提出的 bioZ 读出 IC 的有效性。