Notch Filter - Parallel
The "notch" can be adjusted to a specific frequency, depth and width. The most versatile type of notch filter is the "parallel notch filter" or "parallel trap circuit"; these are two different names for a combination of a resistor, inductor, and capacitor in parallel.These filters are very difficult to design, due to the complex interactions of the non-ideal portions of each componentThe advantages of a parallel notch filter are that they work independently from the impedance of the driver, and can be added to an existing crossover network.