IEEE Trans Biomed Circuits Syst. 2021 Jun;15(3):443-453. doi: 10.1109/TBCAS.2021.3082545. Epub 2021 Aug 12.
A high-pass sigma-delta modulator (HPSDM) is proposed for electrocardiography (ECG) signal acquisition system. The HPSDM is implemented using operational amplifier (op-amp) sharing and programmable feedforward coefficients. The op-amp sharing is adopted to reduce the quantity of amplifiers because they dominate the power consumption of the HPSDM. In addition, given that the magnitude of the ECG is dependent on different persons, programmable feedforward coefficients are utilized to extend the dynamic range of the HPSDM to fit the actual application. The proposed HPSDM is fabricated in a 0.18-μm standard CMOS process. Measurement results reveal that the proposed HPSDM has a signal-to-noise and distortion ratio (SNDR) of 54.5 dB and a power consumption of 2.25 μW under a 1.2 V supply voltage and achieves a figure of merit (FoM) of 12.96 pJ/conv. Moreover, the proposed HPSDM has an SNDR of 64.8 dB and a power consumption of 5.2 μW under a 1.8 V supply voltage and achieves a FoM of 9.15 pJ/conv due to the op-amp sharing technique. Under the 1.2 V and 1.8 V supply voltages, the dynamic range of the HPSDM is extended to approximately 12 dB due to the technique of programmable feedforward coefficients.
提出了一种用于心电图（ECG）信号采集系统的高通 sigma-delta 调制器（HPSDM）。该 HPSDM 采用运算放大器（op-amp）共享和可编程前馈系数来实现。采用 op-amp 共享技术可以减少放大器的数量，因为它们是 HPSDM 功耗的主要来源。此外，由于 ECG 的幅度取决于不同的人，因此采用可编程前馈系数来扩展 HPSDM 的动态范围，以适应实际应用。该 HPSDM 采用 0.18-μm 标准 CMOS 工艺制造。测量结果表明，在 1.2 V 电源电压下，该 HPSDM 的信噪比和失真比（SNDR）为 54.5 dB，功耗为 2.25 μW，实现了 12.96 pJ/conv 的性能指标（FoM）。此外，在 1.8 V 电源电压下，该 HPSDM 的 SNDR 为 64.8 dB，功耗为 5.2 μW，由于采用了 op-amp 共享技术，实现了 9.15 pJ/conv 的 FoM。在 1.2 V 和 1.8 V 电源电压下，由于采用了可编程前馈系数技术，HPSDM 的动态范围扩展了约 12 dB。
