消除端电容对单片晶体滤波器影响的方法

Method of Eliminating the Influence of Terminal Capacitance to Monolithic Crystal Filter

为了解决晶体滤波器与电路前、后级有效匹配连接,并消除端分布电容的影响,提出了一种新的设计方法。该方法采用在滤波器的前后端装加匹配器,匹配器由电感和电容等不消耗有功功率的无功元件构成,因此不会对信号产生较大的传输损耗,也不会使通带特性变差。且匹配器可起到"隔离"分布电容的作用,大大减小分布电容对滤波器端部的影响,具有很好的应用价值。

A new design of monolithic crystal filter was proposed for effectively matched connectivity between the crystal filter and the circuit, also for elimination of the impact of distributed capacitance at the terminals. In the present design, the matcher was introduced between the front and rear terminals, which comprised inductors, capacitors and other reactive components without active power consumption. Honce the signal transmission loss was minimized and the transmission band deterioration could be avoided. Moreover＇ the matcher also served to isolate the stray capacitor and thus alleviated the impact of the stray capacitor to the filter terminals, with a good application in practical use.