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简单的低通滤波器可以当作具有额定的三极0.1dB切比雪夫响应的π型滤波器来配置,以提供适中的阻带选择性。可将四个这样的滤波器装在一个滤波器盒内,然后用板扭式开关来选择滤波档。生产商用分级衰减器和可调基带均衡器的厂商通常都采用这一技术。在可调低通滤波器中,每一部分滤波器电路均使用市售的元器件(图1)。本例中的各部分滤波器电路的截止频率均是用标准的电感和电容器来实现的,而无需任何额外的串联或并联的元器件。固定电感器为Coilcraft 90系列轴向引出扼流圈,容差为±10％;固定电容器是从任意一家供应商那里都可买到的聚丙烯电容器,其中1200pF电容器的容差为±2%,
A simple low-pass filter can be configured as a π-type filter with a rated tripolar 0.1dB Chebyshev response to provide a moderate stopband selectivity. Four such filters can be housed in a filter box, and the plate can be used to select the filter profile. Manufacturers of commercial step attenuators and tunable baseband equalizers typically use this technology. In the adjustable low-pass filter, each part of the filter circuit using commercially available components (Figure 1). The cut-off frequencies for the various parts of the filter circuit in this example are achieved using standard inductors and capacitors without any additional components in series or parallel. The fixed inductor is a Coilcraft Series 90 axial lead-in choke with a tolerance of ± 10%; the fixed capacitor is a polypropylene capacitor available from any supplier, with a tolerance of ± 2% for a 1200pF capacitor,