第一讲引言一、预备知识 1.模拟滤波器(Butterworth型)及其实现在很多生物医学仪器中(例如心电图机,脑电图机等),模拟滤波器被广泛地用来压缩信号频带和滤去干扰信号。模拟滤波器分两种:无源滤波器和有源滤波器。无源滤波器由电感、电容和电阻构成,这在频率较高或要求较低时是适用的。但在频率较低时,由于电感量较大和品质因数比较低,使滤波效果受到严重的影响,因而是不理想的。生物医 I. INTRODUCTION I. PRELIMINARY KNOWLEDGE 1. Analog Filter (Butterworth Type) and Its Implementation In many biomedical devices (such as electrocardiographs and electroencephalographs), analog filters are widely used to compress signal bands and filters To interfere with the signal. There are two types of analog filters: passive filter and active filter. Passive filters consist of inductors, capacitors and resistors, which are suitable at higher or lower frequencies. However, at lower frequencies, the filtering effect is severely affected due to the large inductance and the low quality factor, which is undesirable. Biomedical