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一、选频: 滤波器(高通、低通或带通)可以是无源的,也可以是有源的。前者是一个传统的电感电容电路,尤其是在声频上、成本高、麻烦并且不能随意选择响应曲线。有源滤波器使用普通电阻电容和运算放大器,成本低、容易调谐,对磁场不敏感,没有噪声,小而轻,不受负载和电源阻抗变化的影响。此外,有源滤波器还易于串联,因而可使合成的滤波器影响响应分裂成不相干扰的简单的因素化方块。
First, the frequency selection: Filters (high-pass, low-pass or band pass) can be passive, it can be active. The former is a traditional inductance and capacitance circuit, especially in the audio frequency, high cost, trouble and can not choose the response curve. Active filters use common resistor and op amps. They are low cost, easy to tune, insensitive to magnetic fields, no noise, small and light, and immune to changes in load and supply impedances. In addition, the active filters are also easy to connect in series, thus allowing the synthesized filter to influence the response to split into simple, non-perturbing, factorized blocks.