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一、概述随着通讯和频率控制技术的迅速发展,滤波器的应用范围越来越广。对滤波器,不仅在稳定性和选择性方面提出了越来越高的要求,而且在带外防卫度方面也提出了严格的要求。滤波器的种类很多,早先是传统的LC滤波器,后来又出现了多种新型滤波器,诸如晶体滤波器、陶瓷滤波器、有源滤波器和数字滤波器等。这里介绍一种5.2兆赫晶体宽带滤波器。主要讨论其带宽的控制和阻带寄生衰减的抑制,并简要介绍滤波器的设计和调试的全过程。分立式晶体宽带滤波器,是由石英谐振器,电容器及电感线圈等分立元件组成。其滤波特性,除了取决于石英谐振器的等效参数以外,还与展宽线圈的关系甚大。晶体滤波器的带宽,取决于石英谐振器的串并谐振和反谐振之间的间隔,即取决于滤波晶体的等效电路的静电容C_0与动态电容C_s之比r,即r=C_0/C_(so)如采用狭带
First, an overview With the rapid development of communications and frequency control technology, the filter is more widely used. The filters not only place increasing demands on stability and selectivity, but also place stringent requirements on out-of-band protection. There are many different kinds of filters. Previously, they were traditional LC filters. Later, many new filters appeared, such as crystal filters, ceramic filters, active filters and digital filters. Here is a 5.2 MHz crystal wideband filter. It mainly discusses the control of its bandwidth and the suppression of stop-band parasitic attenuation, and briefly introduces the whole process of filter design and debugging. Discrete crystal wideband filter, is composed of quartz resonators, capacitors and inductors, and other discrete components. Its filtering characteristics, in addition to the quartz resonator equivalent parameters, but also with the widening coil relationship is very large. The bandwidth of the crystal filter depends on the interval between the string resonance and the anti-resonance of the quartz resonator, ie, the ratio r of the capacitance C_0 and the dynamic capacitance C_s of the equivalent circuit of the filter crystal, ie r = C_0 / C_ (so) Such as the use of tape