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设计了一款基于生物应用的截止频率为38.49 Hz的5阶跨导电容(G_m-C)低通滤波器。首先利用电流互抵技术设计实现了一款低G_m的运算跨导放大器(OTA),并基于此OTA,采用无源电感电容(LC)网络模拟法设计了一款5阶椭圆滤波器。最后基于华虹宏力0.35μm CD350 60 V/80 V工艺应用Spectre仿真工具对滤波器进行仿真。结果表明,所设计的低通滤波器可以实现非常陡峭的过渡带,并在50 Hz工频信号处衰减达-43.812 dB;阻带衰减为-33.18 dB;通带内平均噪声为352.0μV·Hz~(-1/2);总谐波失真为-56.24 d B;3.3 V电源电压下,5阶滤波器总功耗仅为11.73μW。所设计的滤波器可以有效采集频率极低的生物信号并且滤除干扰信号。芯片面积为1 200μm×728μm。
A 5-order transconductance (G_m-C) low-pass filter based on biological applications with a cutoff frequency of 38.49 Hz was designed. First of all, a low G_m transconductance amplifier (OTA) was designed and implemented based on the current offset technology. Based on this OTA, a 5th order elliptic filter was designed by using the LC network simulation method. Lastly, the filter was simulated using Spectre simulation tool based on Hua Hong Grace 0.35μm CD350 60 V / 80 V process. The results show that the designed low-pass filter can achieve a very steep transition band and attenuates up to -43.812 dB at a 50 Hz power frequency signal; the attenuation of the stop band is -33.18 dB; and the average noise in the passband is 352.0 μV · Hz ~ (-1/2). The total harmonic distortion is -56.24 dB. The total power loss of the fifth-order filter is only 11.73μW at 3.3V supply voltage. The designed filter can effectively collect the biological signal with very low frequency and filter out the interference signal. The chip area is 1200 μm × 728 μm.