一种适用于生物电信号处理的全集成五阶Gm-C低通滤波器

摘要

传统的Gm-C滤波器OTA输入晶体管大多工作在饱和区,存在输入动态范围较小和跨导值较大等不足,难以满足生物医学电信号处理滤波器所要求的超低截止频率、低功耗与大输入动态范围等要求,采用将输入晶体管钳位到线性工作区的方法,设计了跨导线性可调的OTA以提高滤波器能够处理的信号幅度.并应用该OTA综合了一种五阶Gm-C超低频低通滤波器.仿真结果表明,该滤波器在1.8 V电源,800 mVpp输入条件下实现了283 Hz的超低低通角频率,-6.4 dB的带内增益,51 dB的三次谐波失真,功耗仅为22 μW,适用于可穿戴式生物医学电信号读取电路.%As the OTA input transistors of traditional Gm-C filter usually operate in the saturated zone and have the disad-vantages of small input dynamic range and large transconductance value,it is difficult to meet the requirements of ultra-low cut-off frequency,low power consumption,and large input dynamic range required by biomedical electrical signal processing filter. Therefore,a linear and tunable transconductance OTA was designed with the method of clamping the input transistor to the lin-ear operation zone to improve the signal amplitude that the filter can process. The OTA is utilized to synthesize a fifth-order Gm-C low-pass filter with ultra-low frequency.The simulation results show that the filter can achieve 283 Hz ultra-low-pass angle frequen-cy,-6.4 dB in-band gain,and 51 dB third harmonic distortion under the input condition of 1.8 V power supply and 800 mVpp. The power consumption of the filter is only 22 μW which is suitable for the wearable biomedical electrical signal readout circuit.