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由于制造低频特别是甚低频高Q值电感遇到很大困难,因此在滤波器中能否不用电感的问题早就提出来了.如果单纯用RC取代LC,要得到尖锐的鉴别特性,则通带内衰耗就很大,以致必需用放大器来补偿.于是有源滤波器就随着生产的要求和技术的进步而发展起来.斯各脱在1938年所发表的窄带RC放大器可以看作是最早的有源滤波器.主要用在选频放大器中.直到1954年林威尔提出使用负阻抗变换器的RC滤波器之后,高阶的传递函数的组成才有了实现的可能.从此有源滤波器的理论和技术才开始有了比较迅速的发展.特别是这以后提出的一些型式的电路除使构成的滤波器有要求的通阻带外,而且在通带内迟延特
The problem of whether or not to use inductors in a filter has long been a problem because of the great difficulty of making low-frequency, especially very low-frequency, high-Q inductors. If simply replacing RC with RC, for sharp discrimination, In-band attenuation is so great that an amplifier must be used to compensate, so that the active filter is developed with production requirements and advances in technology.SSLAT’s narrowband RC amplifier published in 1938 can be seen as The earliest active filter was mainly used in the frequency selective amplifier.While it was not possible for the composition of the higher order transfer function to be realized until after Linwell proposed the RC filter using a negative impedance converter in 1954. From then on, Filter theory and technology began to have relatively rapid development.Especially after some types of circuit proposed in addition to make up the filter required by the passband, but also in the passband delay special