一种适用于心电信号检测的高阶连续时间OTA-C滤波器设计∗

摘要

提出一种适合心电信号( ECG)检测的OTA-C滤波器。为了达到低功耗、低截止频率、高直流增益、高阻带衰减、低谐波失真的目的,滤波器采用五阶巴特沃斯全差分低通滤波结构和高增益的两级单端输出OTA,其中OTA电路采用亚阈值区驱动、电流分流和源极负反馈等技术。采用SMIC 0.18-μm 1P6M CMOS工艺进行电路、版图设计及优化。仿真结果表明,滤波器在静态功耗为17.6μW,截止频率为240 Hz,直流增益为-6 dB,阻带衰减大于72 dB每五倍频,三次谐波失真小于-62 dB在400 mV时,适合应用于心电信号检测模拟前端。%An operational transconductance amplifier-capacitance( OTA-C) filter for electrocardiogram( ECG) Signal Acquisition is presented. To get low power low cut-off frequency high DC gain high stop-band attenuation and low harmonic distortion,the filter uses fifth-order Butterworth fully differential low-pass topology and a two-stages single-ended OTA,which works in sub-threshold region with current division and source degeneration techniques. This cir-cuit and layout are designed and optimized in SMIC 0.18-μm 1P6M CMOS process. The simulation result shows that the amplifier consumes a total power of only 17.6 μW,and achieves a cut-off frequency of 240 Hz,a DC gain of-6 dB,a stop-band attenuation of more than 72 dB@ half a decade,a third harmonic distortion of -62 dB at 400 mV. It could be an attractive candidate for ECG signal acquisition analog front-end.