无源双T陷波器电路(Twin-T passive Notch Filter)
图1是双- T的无源陷波器陷波滤波器电路，陷波器是某一小频率范围内的带阻滤波器。陷波器的一个常见的应用是滤除60赫兹左右的交流电噪声。这一双 T的陷波器最常用的一个陷波滤波器，两个T型网络组成。T网络由一个电阻和两个电容组成，其他有两个电阻和一个电容器则组成另一T型滤波器.如图1所示的陷波频率约在Fn = 1 /（2πRC）。
图1 无波陷波器电路图
A notch filter is a circuit that rejects a very narrow band of frequency. A common application of a notch filter is the removal of the 60-Hz hum from an AC line. The twin-T filter, one of the most commonly used notch filters, is a passive filter composed of two T-networks. One of these T networks has one resistor and two capacitors, while the other has two resistors and one capacitor. For the twin-T notch filter in Figure 1, maximum attenuation occurs at fn = 1/(2πRC).