晶体相位补偿网络及在线性相位滤波器中的应用

Crystal Phase Conpensation Network and Its Application on Linear Phase-Shift Crystal Filter

介绍一种晶体相位补偿网络,在幅频特性上,它是一种全通网络。但它能在晶体滤波器带宽范围内提供相位补偿,这样由一个普通晶体滤波器加一个晶体相位补偿器就可以组成一个线性相位晶体滤波器,同时也使线性相位晶体滤波器的设计带宽得以增加。设计更为灵活。文中也给出了一个21.85 MH z,3 dB带宽为70 kH z的线性相位滤波器的实例,其带内群时延波动≤±0.6μs。该方法可为解决滤波器幅频特性和相频特性的矛盾,提供一种新的较为灵活的折衷方案。

A crystal phase compensation network is introduced in this paper. On magnitude-frequency characteristic,it is an all-pass network. But it can provide phase compensation within crystal filter bandwidth. Then we can get a linear phase crystal fileter composed of a common crystal filter and a crystal phase compensation network. So ,the designed bandwidth of linear phase crystal filter is increased and the design is more flexible. As an example,a 21.85 MHz linear phase crystal filter is presented. Its 3 dB bandwidth is 70 kHz and group delay ripple is =-±0.6 μs. As description,this method provides a novel and flexible compromised solution for resolving conflict between filter＇s magnitude-frequency characteristic and phase-frequency characteristic.